Fight of the year: Pac-Marquez IV

It lasted just six rounds, but Juan Manuel Marquez-Manny Pacquiao IV gave fans a fight to remember. John Gurzinski/AFP/Getty Images

When Top Rank put together a fourth helping of the Manny Pacquiao-Juan Manuel Marquez rivalry, many were disappointed. Not because it probably wouldn't be a good fight, but because of general fatigue over the matchup. Give us something fresh, many said.

Of course, the first three fights between the great rivals were excellent -- rousing battles at the highest level of boxing that were competitive and compelling. And even though Pacquiao led 2-0-1, all three decisions were highly controversial and could have gone either way.

So when they did meet Dec. 8 in a welterweight showdown at the MGM Grand in Las Vegas, expectations were for another exciting fight even if it hadn't been the fans' top choice of a match for either man. That hardly matters now, however, because their fourth fight -- rounds 37-42 of an historical series -- turned out to be the best of the bunch.

It offered a festive and raucous atmosphere, thrilling two-way action, multiple knockdowns, blood and one of the most significant and violent knockouts in history as Filipino icon Pacquiao -- the all-time great eight-division champion and former pound-for-pound No. 1 -- went down face-first with one second left in the sixth round.

The shocking conclusion -- the 2012 ESPN.com knockout of the year -- was simply the end of what turned out to be the 2012 ESPN.com fight of the year.

The action heated up in the second round as Pacquiao rocked Marquez with two straight left hands, his money punch, and had him off balance with his feints and head movement. But with the heavily pro-Marquez crowd chanting "Mexico! Mexico! Mexico!," Marquez landed a right-hand bolt midway through the third round to drop Pacquiao hard, the first knockdown he had scored in the series after being down four times himself.

Pacquiao was shaky after the knockdown, but they spent the rest of the round engaged in fierce exchanges. The tension continued to build in the fourth round before the electrifying fifth became the best round of the rivalry. Pacquiao landed another straight left hand in the second minute, forcing Marquez to touch his glove to the canvas for a knockdown. Marquez was not badly hurt and immediately hammered Pacquiao with a huge right hand.

"This might be the best fight yet," HBO analyst Larry Merchant said. Responded Jim Lampley, his longtime broadcast partner, "This has been a blood-curdling war so far!"

Pacquiao badly hurt Marquez, who was now bleeding from his nose, with a right hand in the toe-to-toe final minute, prompting Lampley to exclaim at the bell, "All-out war in Vegas!"

Pacquiao looked like he was closing in on a stoppage in the sixth round after continuing to land heavy, damaging shots. But then Pacquiao got a little lazy on defense and Marquez stepped into a full-force right hand that knocked Pacquiao out cold to bring the epic fight to an abrupt and stunning conclusion.

"What an amazing fight," Lampley cried. "What an amazing, stunning knockout performance from Marquez!"

Other unforgettables

Brandon Rios TKO7 Mike Alvarado (Oct. 13 at Carson, Calif.): From the moment this junior welterweight fight was made, expectations were sky-high for a memorable battle. They more than lived up to the hype, one brutal punch at a time. In most years, this violent clash would be the fight of the year. For the entire fight, they blasted each other with hard shots like a game of rock 'em, sock 'em robots. They combined to throw 190 punches in the first round and never let up, fighting at a pace more akin to a video game than a real fight. Neither man took a backward step, and there were numerous fierce exchanges. They were both rocked and marked up as they emptied their tanks while showing enormous toughness. Round 5 was a legit round of the year candidate filled with blazing action. The fight was even on two scorecards going into the seventh round, but Rios finally got to Alvarado, hurting him with a right hand and pouring it on until his head snapped back, forcing referee Pat Russell to stopped the fireworks-filled slugfest.

Orlando Salido TKO10 Juan Manuel Lopez II (March 10 at San Juan, Puerto Rico): When Salido stopped Lopez in front of his Puerto Rican crowd to win a featherweight belt in 2011, it was one of best fights of the year. The rematch was even better as they banged it out for 10 tough rounds before Salido got a second straight upset knockout. But before the stoppage, it was a wild, action-packed affair. The outright brawl will go down as one of the most exciting title fights in the storied Mexico-Puerto Rico rivalry. The action really picked up in the fourth round, Lopez dropped Salido in the fifth and the action continued to build through the superb eighth round and epic ninth. By the 10th, Lopez was fading and went down on a nasty combination to give Salido another memorable victory and fans another barn burner.

Robert Guerrero W12 Andre Berto (Nov. 24 at Ontario, Calif.): Berto has been in exciting fights, and Guerrero has been an underrated action fighter, so when they met for Guerrero's interim welterweight belt, there were considerable expectations for the fight. They delivered big time in a bruising rumble. Guerrero dropped Berto in the first and second rounds and they fouled each other repeatedly throughout the fight. Berto, although trailing, was game and fought his heart out despite both eyes being nearly closed by the final third of the fight. The seventh round was a round of the year candidate. "This is a street fight," Lampley said as they exchanged at the end of the round. "This could take place on asphalt in a back alley. This would gather a crowd anywhere it took place."

Mike Alvarado W10 Mauricio Herrera (April 14 at Las Vegas): When is Alvarado ever in a bad fight? Almost never, and this junior welterweight tussle filled with blood and toe-to-toe combat was no exception. Although Alvarado generally was in command, this was a brawl as they traded flush bombs. The second and third rounds were hellacious and filled with unrelenting action. Herrera, who fought off the ropes while Alvarado pressured him, began to bust up Alvarado's right eye in the fourth round. Herrera's nose was bleeding in the fifth. Alvarado shifted into another gear in the second half of the fight and Herrera, his left eye a swollen mess, did everything he could to stay with him.

Brian Viloria TKO10 Hernan "Tyson" Marquez (Nov. 17 at Los Angeles): Often it's little guys who deliver huge action and that was the case in this flyweight unification fight that lived up to the hype. Marquez rocked Viloria and sent him reeling in the first round. Viloria responded by nailing Marquez with a right to drop him just before the round ended. The action never subsided, especially in the round of the year candidate fifth, when Marquez staggered Viloria and had him in trouble before Viloria rallied to drop Marquez. Early in the 10th, they were in yet another heated exchange when Viloria pounded Marquez with a left hook that dropped him flat on his back. He beat the count, but as Viloria was nailing him in the follow-up attack, Robert Garcia, Marquez's trainer, threw in the towel.

Roman Gonzalez W12 Juan Francisco Estrada (Nov. 17 at Los Angeles): Gonzalez's junior flyweight title defense was overshadowed by the sensational Viloria-Marquez main event, making this the best undercard fight of 2012. Gonzalez, a huge puncher, couldn't get Estrada out of there and settled for a decision in a high-energy battle worthy of having been the main event. It was a fast-paced, all-action brawl that had good ebb and flow. Virtually every round was action-packed. Gonzalez landed many heavy blows, but Estrada took 'em all and dished out enough to keep it very interesting.

Marcos Maidana TKO8 Jesus Soto Karass (Sept. 15 at Las Vegas): This welterweight gem was part of a four-fight card dubbed "Knockout Kings" and it stole the show. Maidana, a bruising brawler, and Soto Karass, also and action fighter, meshed perfectly in a thrilling shootout. They spent the entire fight battling, landing clean shots and giving fans what they wanted. Maidana was in control, but Soto Karass always seemed like he was one punch away from taking over. They engaged in some rough stuff, which drew point deductions, before Maidana landed his best punch, a clean overhand right that dropped Soto Karass in the closing moments of the seventh round. Soto Karass was still shaky in the eighth and Maidana teed off until referee Kenny Bayless halted the slugfest.

Roman "Rocky" Martinez W12 Miguel Beltran Jr. (Sept. 15 at Las Vegas): Most of the drama from this card came in the 12th round of the Sergio Martinez-Julio Cesar Chavez Jr. main event, but this undercard bout served up plenty of sustained and bloody action in a very competitive scrap as Martinez won a split decision to claim a vacant junior lightweight belt. It was a thrilling, bloody, back-and-forth fight with numerous close rounds and lots of clean punching, marred only by a ticky-tack point deduction by referee Russell Mora, which cost Beltran a draw.

Marco Huck D12 Ola Afolabi II (May 5 at Erfurt, Germany): When they met in 2009, Huck retained his cruiserweight title in a close fight. But it was nothing like this grinding battle. Huck was lucky to escape with his title after a draw in a very tough fight. Afolabi dominated early and appeared to drop Huck with a right late in the second round, but referee Robert Byrd ruled it a slip. Afolabi bloodied Huck's nose in the third. Huck had Afolabi in deep trouble and close to going down before the bell ended the ninth. The action went to another level in the outstanding 12th round when they pounded on each other with abandon. Trilogy, anyone?

Kazuto Ioka W12 Akira Yaegashi (June 20 at Osaka, Japan): Yaegashi stopped Pornsawan Porpramook in the 10th round to win a strawweight title in the epic 2011 fight of the year. In 2012, he lost a fabulous fight as he and Ioka met in the first all-Japanese title unification match. They delivered a competitive and action-packed fight in which Yaegashi persevered with a terribly swollen left eye, making one wonder if he would be able to finish the fight. That just added to the drama of a great battle.

Floyd Mayweather Jr. W12 Miguel Cotto (May 5 at Las Vegas): Even though Mayweather clearly won to claim Cotto's junior middleweight belt, Cotto gave him perhaps the toughest, most physical fight of his great career. Not only was it the year's biggest fight (1.5 million pay-per-view buys), it was also one of the most entertaining and satisfying for those who laid out the cash. Maybe, at 35, Mayweather has lost a step, which allowed Cotto to connect frequently. Maybe, as Mayweather said, he wanted to give fans excitement. Whatever it was, Mayweather, with a bloody nose, slugged it out with a bigger guy, whom he badly wobbled in the 12th round to conclude the most exciting fight of his career.