Lionel Messi has won six Spanish league titles, three Champions League crowns and a record four world player-of-the-year awards. But he hasn't won a World Cup.
Cristiano Ronaldo won nine trophies with England's Manchester United, four more with Real Madrid in Spain and is a two-time world player of the year. But he too has never won a World Cup.
Together they have scored nearly 800 goals for club and country over the last decade. Yet if they both come home from this summer's World Cup empty-handed again, the number that might ultimately come to define their careers is zero.
Just ask Messi.
"I don't think any player can be considered a true great until they have won the World Cup," Messi told Goal.com last week. "I hope that I can do that and I hope I can do that this summer. But until then I don't talk about me as the best."
Everybody else does, though.
"He's the best. There is no other like him," said Pep Guardiola, Messi's former club coach at Barcelona. "We'll never see a player like him again."
Arsenal Coach Arsene Wenger agreed, comparing Messi to a character in a video game.
"He made the impossible possible," he said. "He is unstoppable. He is the best player in the world by some distance."
If Messi truly is a superman, though, then the World Cup is his kryptonite. In eight matches over two World Cups he has scored only once, with Argentina losing in the quarterfinals both times.
That's far from great. And Messi knows it.
"Messi might be regarded as the greatest player in the whole history of the game, but he would give all the medals he has won with Barcelona just to win one World Cup, that is how important it is for him," former Argentine midfielder — and World Cup champion — Ossie Ardiles said last week at a soccer forum in Jordan.
"To be considered alongside the top, top guys like Pele and Diego Maradona and so on, he not only needs to be in the World Cup but to win it."
This could be the summer that happens. Although host Brazil and European giants Spain and Germany are considered the tournament favorites, Argentina is ranked seventh in the world and, significantly, it has won the World Cup the last two times it was held in Latin America.
Plus Argentina is greatly improved from four years ago and will surround Messi with experienced, world-class players including Sergio Aguero and his Manchester City teammates Pablo Zabaleta and Martin Demichelis; Gonzalo Higuain of Italian club Napoli; Ronaldo's Real Madrid teammate Angel Di Maria; and Barcelona's Javier Mascherano.
Also working in Messi's favor is the fact Argentina is the giant of what appears to be a relatively easy group that includes Bosnia-Herzegovina, Iran and Nigeria, none in the top 24 in the latest FIFA world rankings.
Then there's his youth: Messi turns 27 next month, so even if he falls short this year he figures to have another shot at a World Cup title four years from now in Russia.
But he promises he isn't playing for his legacy in Brazil. He's playing for Argentina.
"I do not want to be world champion … so that people can say that I will be a great like Pele or Maradona," he told ESPN. "I want to do it to achieve this objective with the national team."
Portugal's Ronaldo — who, at 29, might be facing his last chance at a world championship — has said pretty much the same thing.