Move over, xG! LaLiga's new 'Goal Probability' metric sheds new light on classic goals from Cristiano Ronaldo, Lionel Messi and more

Expected goals (xG) has become the standard method to measure the quality of a shot at goal by calculating the likelihood of it hitting the back of the net. The advanced metric has been embraced by some fans, and left others non-plussed at reading that their team had an xG, for instance, of 0.93 after a match. But now, LaLiga has developed its own "Goal Probability" metric that shows visually the percentage chance of a goal being scored by any player at any given moment during any match in the Spanish top flight, and it has been applied to some of the most amazing goals ever seen in the history of the league from the likes of former Real Madrid great Cristiano Ronaldo and ex-Barcelona icon Lionel Messi.

LaLiga's new metric takes into account the attacking and defending players' positions on the pitch among nine variables to calculate the probability of the shooter being able to convert the chance as a percentage rating between 0-100%.

The attacker's distance from goal, proximity to defenders, the positioning of the goalkeeper, and the shooter's ability are all factors, as is the nature of the chance in question -- be it a one-vs.-one, a simple tap-in, or even a thunderbolt volley from 30 yards.

The Goal Probability metric was established using a process that involved trawling through over 2,000 LaLiga matches to review and analyse more than 20,000 shots on goal in order to crunch the data and produce a viable mathematical model.

In simple terms, a world-class striker with the ball at their feet and an open goal at their mercy will produce a Goal Probability close to 100%, whereas a goalkeeper waiting patiently at the far end of the pitch will have a chance close to 0%.

Goal Probability can be calculated in real time and delivered in roughly 30 seconds, thus allowing graphics to be produced for live television replays. It can also be applied retrospectively, allowing us to revisit some classic LaLiga goals from the past 30 years to evaluate the precise chance they each had of hitting the back of the net.

Spoiler alert: They all go in!

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Cristiano Ronaldo (Real Madrid vs. Espanyol, 2016)

LaLiga Goal Probability: Cristiano Ronaldo (Real Madrid vs. Espanyol, 2016)

Watch how Cristiano Ronaldo upped his Goal Probability with some fancy footwork vs. Espanyol.

Espanyol were doubtlessly sick of the sight of Real Madrid by the time the 2015-16 LaLiga season was over after losing by an aggregate of 12-0 over their two games. Los Blancos won both fixtures 6-0 with Ronaldo helping himself to eight of them -- the first five goals coming in the first encounter in early September at the RCDE Stadium and the other three forming a perfect hat trick in the second rout in Madrid in late January.

The second goal of his treble at the Bernabeu came on the stroke of half-time with Ronaldo hurtling on to a deflected pass from James Rodriguez and bursting toward the edge of the Espanyol area, pursued by defender Enzo Roco. Having been closed down and temporarily stopped in his tracks by Roco, Ronaldo's Goal Probability rating was 2.6%. However, that soon crept up to 5.3% as the Portugal captain chopped inside and left his marker scrambling in his wake.

Ronaldo was then surrounded by a clutch of three recovering Espanyol defenders. But he once again maneuvered into space with a quick-footed shimmy that brought him an unhindered shooting opportunity in a central position with a 13.8% chance of success. It was at this precise point that a left-footed shot was cracked past goalkeeper Giedrius Arlauskis from 18 yards.

Lionel Messi (Real Betis vs. Barcelona, 2019)

LaLiga Goal Probability: Lionel Messi (Real Betis vs. Barcelona, 2019)

Lionel Messi defied the Goal Probability odds with this stunning chip.

After losing 4-3 at Camp Nou earlier in the 2018-19 season, Barcelona wrought revenge on Betis with a 4-1 drubbing at the Estadio Benito Villamarin when the two sides met again in mid-March. Messi was at his imperious best, scoring three of Barca's four goals in a hat trick that concluded in the 85th minute with one of the best of his career.

The Argentina captain began the approach by shuffling past Betis striker Lorenzo Moron, who had tracked back in a bid to aid his defence. Messi then laid a simple pass out to Ivan Rakitic on the left-hand side of the area and made himself available for a quick return pass. Messi then proceeded to arc a perfect first-time chip over the heads of six players and in off the Betis crossbar. As with the Ronaldo chance above, the Goal Probability rating of 7.1% here is only so high for such an extraordinary weighted lob because of Messi's status as a Category 3 attacker.

Diego Costa (Atletico Madrid vs. Getafe, 2013)

LaLiga Goal Probability: Diego Costa (Atletico Madrid vs. Getafe, 2013)

Diego Costa produced an unbelievable acrobatic finish on his way to a 27-goal LaLiga season.

A key factor in Atletico's run to the 2013-14 title was the impressive goal haul of Diego Costa, who scored 27 times in just 35 league games for Diego Simeone's uncompromising side en route to the championship. The Brazil-born striker notched his 14th goal of the campaign against Getafe at the Vicente Calderon in November, the fifth in his side's 7-0 trouncing of the Azulones.

Costa found himself in a slightly awkward position when Gabi's looping cross from the right flank found the forward in the centre of Getafe's penalty area, dropping both behind him and above head height. There was no option but to take to the air, with Costa contorting his body to connect with an instinctive overhead kick that offered a 6.2% chance of going in at the point of contact. Sure enough, the acrobatic shot flew past Getafe keeper Miguel Angel Moya, who could only stand rooted to the spot, looking on incredulously as the net bulged once again.

Sergio Ramos (Barcelona vs. Real Madrid, 2007)

LaLiga Goal Probability: Damian Suarez (Getafe vs. Espanyol, 2018)

Damian Suarez scored his first ever Getafe goal in amazing style and with a Goal Probability of just 2.2%.

With the 2006-07 campaign entering its latter stages, Barca faced Madrid at Camp Nou in March, desperate for a vital Clasico win. A flurry of goals came in the opening stages with the teams level at 2-2 inside the first half-hour thanks to matching braces from Ruud van Nistelrooy (5' and 13') for Madrid and Messi (11' and 28') for Barca.

It wasn't until the 73rd minute that Los Blancos seized the lead again when Ramos popped up to put the visitors ahead at 3-2 in front. Guti sent over an in-swinging free kick from the right into the Barca penalty area which found the distinctive headband of Madrid defender Ramos, who was actually facing toward Guti with his back to goal and under duress from Barca centre-back Carles Puyol. However, despite the low Goal Probability of 2.8%, he still managed to produce an effort on goal with a reverse diving header that flicked past Victor Valdes and in off the bar. It wasn't enough from Real as a third goal from Messi in the 91st minute -- sealing his first hat trick for the club -- saw the pulsating clash end in a 3-3 draw

Damian Suarez (Getafe vs. Espanyol, 2018)

LaLiga Goal Probability: Chimy Avila (Athletic Club vs. Huesco, 2018)

Late equalizers don't come much better than Chimy Avila's moment of genius against Bilbao.

Getafe rose up into the top eight of LaLiga thanks a string of decent results in the final third of the 2017-18 season, with a 1-0 home victory over Espanyol in March sparking a streak of five wins for the Azulones in their last seven games. The only goal of the game came from an unlikely source in right-back Suarez, who netted his first goal for the club (he has since gone onto amass three goals in 244 appearances) in rather spectacular fashion.

A free kick 30 yards from the Espanyol goal was laid off square by Faycal Fajr for Suarez to hit -- and hit it he did as the Uruguayan right-back sent an unstoppable piledriver into the top corner. At the moment Suarez made contact with the ball, the Goal Probability ranking stood at just 2.2% due mainly to distance, allied with the total of 17 players from either team stood between the shooter and the goal. Nevertheless, the shot arrowed past the wall, a charging defender, and Espanyol keeper Vicente Guaita on its way in.

Chimy Avila (Athletic Club vs. Huesco, 2018)

LaLiga Goal Probability: Roberto Carlos (Tenerife vs. Real Madrid, 1998)

Roberto Carlos scored from where only Roberto Carlos could have to notch one of football's iconic goals.

Newly promoted Huesca left it until very late to grab a dramatic equaliser against Athletic Club early in the 2018-19 campaign. On-loan Argentine striker Avila had only been on the pitch for 10 minutes when he waded in with his first-ever goal in LaLiga.

After the ball had pinged around the edge of the Bilbao box it found its way to the feet of Avila, who chipped it up above his waist with his right foot, pivoted through 180 degrees and hit a perfect volley with his left that arrowed past Unai Simon and into the roof of the net. Given the difficult nature of his technique and his relatively modest career goal return to that point, Avila was calculated to have a 1.9% chance of succeeding with his audacious effort.

Roberto Carlos (Tenerife vs. Real Madrid, 1998)

LaLiga Goal Probability: Ronaldinho (Barcelona vs. Sevilla, 2003)

This Ronaldinho moment of magic had just a Goal Probability of just 1.5% when the Brazilian took aim from 30 yards.

Real Madrid's league game against Tenerife in February 1998 lingers in the memory for two reasons: firstly, title-chasing Los Blancos slumped to a shock 4-3 defeat in the Canary Islands despite going ahead twice and secondly, it played host to one of Roberto Carlos' "impossible" goals. The Brazilian left-back took less than a minute after the restart to draw Real level with an emphatic strike that seemed to defy the fundamental laws of physics. Scampering after a ball down the left channel, he caught everybody on the hop by shooting from an almost non-existent angle rather than cross. The swerving drive was lashed Tenerife keeper Marcelo Ojeda and inside the far post.

The application of LaLiga's Goal Probability formula suggests that, while Roberto Carlos' goal wasn't strictly impossible in the literal sense, it still managed to overcome a 1.8% chance of success at the point of contact. A combination of the massively acute angle, the distance from goal, and the fact that he still had the keeper to beat meant that the Real defender needed to pull something truly remarkable out of the bag if he was going to score with his first-time effort.

Ronaldinho (Barcelona vs. Sevilla, 2003)

LaLiga Goal Probability: Rivaldo (Barcelona vs. Valencia, 2001)

Rivaldo rounded off a hat trick in stunning style, with an overhead kick from the edge of the area.

Barca had to rely on a moment of inspiration from their Brazilian genius to rescue a point from the game just as the hour mark approached. Having just recently joined from Paris Saint-Germain, it was the 23-year-old Ronaldinho's first competitive goal for Barcelona in his very first home game, giving the Camp Nou cules a dazzling glimpse of the entertainment that would follow over the next five years.

Ronaldinho burst forward from his own half and sidestepped past two Sevilla defenders before opting to shoot from roughly 30 yards with the slim 1.5% chance of success. Despite his central position, Ronaldinho's Goal Probability was considerably reduced by the distance from goal, the proximity of three defenders directly in front of him and the goalkeeper behind them. However, a perfect connection resulted in the long-range shot dipping wildly before thundering in off the crossbar.

Rivaldo (Barcelona vs. Valencia, 2001)

LaLiga Goal Probability: David Villa (Deportivo La Coruna vs. Valencia, 2006)

Known for his presence in the box, David Villa scored from a little bit further out against Valencia in 2006.

One of the best individual goals ever scored by a Barcelona player, Rivaldo's outrageous strike to claim a hat trick against Valencia at the end of the 2000-01 season was the climax of one of the all-time great individual performances. Fourth-placed Barca needed a win at home against fifth-placed Valencia in the final league game of the campaign to seal Champions League qualification, and they got it thanks to their Brazilian maestro.

The score was locked at 2-2 as the 90th minute loomed when Rivaldo received Frank de Boer's lofted pass on the edge of the Valencia area. As the ball hovered awkwardly above his head, Rivaldo delved deep into his box of tricks in search of one last masterstroke. Facing the wrong way with the ball above him and a five-man defensive block between himself and the target, the Goal Probability for Rivaldo beating Santiago Canizares with any shot from that position was a meagre 1.1%. One supremely executed right-footed overhead kick later and Barcelona were in the hat for the following year's Champions League thanks almost entirely to Rivaldo's 21st, 22nd, and 23rd goals of the season.

David Villa (Deportivo La Coruna vs. Valencia, 2006)

Villa made quite the splash at Valencia in his debut season, scoring 28 goals in 47 appearances for Los Che after moving from Real Zaragoza for €12 million in the summer of 2005. The best of the bunch -- and quite possibly the best goal El Guaje ever scored -- came on matchday 22 of the 2005-06 campaign.

Valencia were second in LaLiga around the turn of the year and fighting hard to keep pace with Barcelona and Real Madrid at the top of the table. Quique Sanchez Flores' side capitalised on a flash of improvisation from Villa when the striker had the ball at his feet just over the halfway line. After taking one touch to dart away from his marker, Villa found a split second to look up, spot Deportivo keeper Jose Francisco Molina off his line line and take aim from 55 yards out.

Unsurprisingly, Villa had a mere 0.5% Goal Probability due to the vast distance his shot had to travel, coupled with the fact that most of the Deportivo defence were in position, and Molina was still technically stood between the posts. But that didn't seem to matter much by the time Villa and the rest of his teammates were celebrating in a jubilant bundle on the floor seconds later.