Players who must master the clay crucible

The European clay-court circuit, the second segment of the Grand Slam year, begins in earnest Tuesday for the ATP at Monte Carlo. The men have really built something valuable and durable in this circuit; I think of it as the "Roland Garros Series," a more successful version of what the USTA has tried to create with its U.S. Open Series.

So let's look at three players who have the most to gain during the tournaments leading up to and including the French Open:

Novak Djokovic, ATP No. 2: Nothing can diminish the credibility of his 24-0 start to 2011, especially because it occurred on a specific surface -- the most common surface, in fact, for the game.

But a strong clay-court season featuring a Masters title and -- dare we think it? -- a triumph over Nadal somewhere along the way would really help his cause, because you need to be able to beat Nadal on clay just as much as you need to beat Roger Federer on grass, or it's hard to prove you've got the chops to be No. 1. Djokovic also could wipe away questions about his stamina with a great clay-court season.

Nadal is 5-0 against Djokovic on clay in the spring (excluding matches at Roland Garros), although their last meeting was that Madrid epic of 2009, in which Nadal only squeaked by 7-6 (9) in the third. Djokovic's decision to skip Monte Carlo with a bad knee (of which there was no sign when he won at Miami just a week ago) suggests that he's resting and gearing up for a push.

Andy Murray, ATP No. 4: Murray could not only benefit from a good clay-court season, he absolutely needs one to balance out the horrible way he's played since his straight-sets loss to Novak Djokovic in the Australian Open final.

The problem is that Murray, like Djokovic, is at his best on hard courts. And having played so poorly on that surface, he squandered a lot of the capital he might have saved for a rainy day in Europe, where the clay plays especially slow when it's damp. Murray has a been a patsy for clay-courters in the David Ferrer mold (Ferrer had back-to-back wins over Murray in the Rome and Madrid Masters last year); heck, Murray has even lost to James Blake on clay (Hamburg).

Until now, Murray never has had to do well on clay because of his hard-court prowess. He's got enough game to contend on the surface, but is he willing to grind? He'll have to, in order to retain his status.

Juan Martin del Potro, No. 45: We all know that del Potro, who missed almost all of 2010 because of complications (including surgery) with an injured right wrist, is already far better than that No. 45 ranking suggests. But a good clay-court season will really position him to make a run this summer on the hard courts, where he's been a Grand Slam champion (U.S. Open, 2009) and collected enough wins to hit a career-high No. 4.

DelPo is only 5-3 for his career on the spring European circuit, but he was a semifinalist at the French Open in 2009, the first time this now 22-year-old youth survived the second round. The big issue for DelPo is likely to be stamina; since he's really just back this year, will he be able to handle the workload on clay? With no rankings points to defend, he will at least be playing without any pressure whatsoever.