Cristiano Ronaldo's ambition means he could play at Qatar 2022

SOCHI, Russia -- The "will he or won't he?" debate about whether Cristiano Ronaldo will attempt to play in a fifth World Cup in four years' time can start in earnest following Portugal's elimination from Russia 2018 at the round-of-16 stage by Uruguay.

It has already begun for Lionel Messi, who was also given his boarding pass for a flight home on Saturday when Argentina fell to a 4-3 defeat vs. France in Kazan -- but the two superstars have wholly different issues to consider before making a decision regarding their international future.

Messi came to life in Argentina's do-or-die group game against Nigeria, scoring a stunning goal and inspiring a 2-1 victory, but he has often looked crushed by the weight of expectancy that comes with leading a football nation as demanding and historically successful as Argentina.

Ronaldo, however, appears energised whenever he wears the Portuguese badge on his chest. He is the global image of his nation and relishes the pressure that comes with being the man expected to deliver. And the big question is whether he is ready -- or even contemplating -- to give all of that up.

Ronaldo will be three months short of his 38th birthday when Qatar 2022 kicks off, but, while it remains to be seen if he will be there, Portugal coach Fernando Santos is confident his captain will continue beyond Russia.

"Cristiano still has a lot to give to football," said Santos. "There is a tournament [UEFA Nations League] in September, and we hope Cristiano will be with us to help the players grow."

Whereas Ronaldo is loved and cherished by Portugal, Messi plays for a poor Argentina team that is unlikely to be good enough to win a World Cup until 2026 at the earliest, and the Barcelona forward will be long gone by then.

Argentina have not won Copa America for 25 years, and so every time Messi pulls on his country's shirt, he knows he is representing a failing generation that has proven unable to match the feats of the 1978 World Cup winners, nor the Diego Maradona-inspired world champions of eight years later or the continental champions of 1991 and 1993.

Ronaldo does not have to shoulder the same burden. Portugal, ironically after their talisman limped off early due to injury in the final against France, achieved their dreams by winning Euro 2016, so this small European nation has already savoured a success it perhaps never truly imagined.

Forty million Argentinians will demand to know why Messi & Co. are returning home early after failing to win it for a third time, whereas nobody really envisaged Portugal as World Cup winners in Russia.

It means Ronaldo can go home knowing his status as a national hero is secure, so what happens next is all about his own ambition and insatiable appetite for creating records and raising his own bar.

Not that this latest exit, which came courtesy of two Edinson Cavani wonder goals for Uruguay, will have not hurt. Ronaldo's best chance to win the game's biggest prize probably came in 2006, when a great team including Luis Figo, Deco and Ricardo Carvalho suffered a 1-0 semifinal defeat against France.

And so, as Messi and Ronaldo consider what to do next, there is a difference: Messi must ask if he wants to continue to expose himself to the draining pressure of playing for Argentina, while Ronaldo's dilemma is whether a four-year wait for Qatar is a price worth paying for the adulation he gets whenever he plays for Portugal.

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There is no question that Ronaldo is still capable of performing at this level. He scored four goals in Russia, including a memorable hat trick against Spain, and while he struggled to make a difference against Uruguay, he has plenty left in the tank and will want to create more history. So, what are his targets?

He stands second in the list of all-time international goal-scorers after eclipsing Ferenc Puskas as Europe's No. 1 with No. 85 vs. Morocco. The world record is held by Iran's Ali Daei, who scored 109; if Ronaldo continues for another four years, that tally might not be beyond him. At the very least, you can bet that Ronaldo will want to break the 100-goal barrier for his country.

And when it comes to playing in World Cups, only two outfield players -- Germany's 1990 World Cup-winning captain Lothar Matthaus and Rafa Marquez of Mexico, who made history in this tournament -- have played in five different tournaments.

That is an achievement Ronaldo could match if he plays in Qatar and is representative of the remaining goals he might be able to fulfill. It is no longer about winning the World Cup; his targets are predominantly personal.

So do not be surprised if he turns up in Qatar, because he just does not look ready to declare Russia 2018 as his international farewell.