PARIS -- There is a long-running debate over whether men's tennis has a big four or just a big three -- or even just a big two or a big one, all depending on who's winning and who is seen as having a chance to win.
Right now, a case could be made for any of the configurations: Novak Djokovic has won the past three Grand Slams -- a big one. Djokovic and Rafael Nadal have played the past three Grand Slam finals -- a big two.
Roger Federer was the last player to defeat Djokovic at a Grand Slam and is the only other one to have won multiple Masters events over the past year. He is seen as a threat at every Slam -- a big three.
Andy Murray has been knocking on the door of a Grand Slam victory for a long time. He has defeated all three of the others in the past and has three Slam finals and multiple Masters to his name -- a big four.
But at this French Open, a slightly different question emerges: If there is a big four, then who is the fourth? Murray has been stuck solidly in that position for quite a few years now, in ways both good and bad. He has reached the final and semifinals of the past two Australian Opens and made the semifinals of the other three Grand Slams in between. But Murray has fallen to one of the top three each time. When it comes to being close, no one else has come close.
For a number of reasons, though, Murray has faded into the background at this year's French Open. Clay is not his preferred surface, despite his junior training in Barcelona and a crafty game that should otherwise work well on this surface. He has been struggling with a back problem, and his results during the warm-up clay events were lackluster. And if he couldn't beat Nadal or Djokovic at the past two hard-court Slams, he's certainly not expected to turn around and do it here.
The Scot's prospects took another dive after he experienced more injury problems during his second-round match against Jarkko Nieminen, receiving treatment on his back down 3-0 in the first set and admitting afterward that he had been "a few points away" from quitting in the second set.
"I just couldn't believe I had won," Murray said.
It turns out the problem was not the same long-running back injury he has been dealing with this season. Instead, it appears to be a muscle spasm that flared up overnight, and Murray decided to play after being examined by his physio.
"His advice before the match was that by playing you're not going to do any permanent damage, so go out and give it a go, see how it feels," Murray said. "I have no idea what will happen in two days. But if it's something like a spasm, it's not like you're doing major damage. You know, it's just a really, really tight muscle."
Last year, Murray made it all the way to the semifinals on an injured ankle, so he can't be counted out yet. But it all adds to the doubts surrounding him at this event. Even before the tournament began, Boris Becker told a British newspaper that if Murray wasn't fully fit, he had no realistic chance of winning and should pull out of the event.
Not that Murray cares about the chatter.
"I mean, it depends how you feel in yourself," Murray said after his first-round win. "And if you think you can win the event, then that's really all that matters. Whether I'm more of a favorite here or at Wimbledon or wherever, it doesn't make any huge difference to how I play or how I approach an event."
Although Murray might believe in his chances, he has competition in the pecking order this fortnight. David Ferrer is No. 6 in the world but has been the second-most successful player on clay this season in terms of ranking points, trailing only Nadal, the king of clay. Ferrer even has the distinction of having pushed Nadal severely and often during the spring, playing his friend and PlayStation rival very close in the final of Barcelona and in the first set of their Rome semifinal. And apart from an injury-affected loss in Monte Carlo, Ferrer has not lost to anyone but Nadal, Djokovic or Federer since early March, and steamrolled his way to two clay titles in South America this year.
On this surface, then, no one has a better claim to No. 4 than the 30-year-old Spaniard. He faces the eccentric play of Benoit Paire next, and a potential danger match against John Isner in the fourth round. (With Ferrer's consistency and returning ability, however, the danger could be Isner's).
But Ferrer's problem isn't that different from Murray's. How do you beat the top three? The dogged Ferrer is a reliable presence in quarterfinals and semifinals, particularly on his favorite surface, but his relentless, steady game has not been able to match the little extra verve and force of the giants when they are fully fit. He's 0-13 against Federer, 4-15 against Nadal (with injuries, fatigue or youth explaining just about all of those wins), and a slightly better 5-8 against Djokovic (but has lost four of the past five).
"I have those players as landmarks, because they have grown in such a way," Ferrer said. "But I'll play one match after the other."
Appropriately, both Murray and Ferrer landed in the same part of the draw here in Paris and might get a chance to fight it out in the quarterfinals. Then we'll know who the real No. 4 is.