Roger Federer may be No. 1 in the ATP rankings, but even he admits that Rafael Nadal will be the top pick to win the French Open. The difference is underfoot. Nadal hasn't lost a match on clay all season and had never lost a match on Parisian clay until last year. Although Federer will be the defending champion, he has never been as dominant on the red stuff as elsewhere and lost to Nadal last week in Madrid just as he has all four times they have met at the French Open.
Here's a look at which other players have been hot on clay this season and who hasn't been up to scratch.
It's quite plain there's been a reign of Spain -- six of the top 10 names on the clay-court list, including all the top four, are Spaniards. Many Spaniards have competed on the final weekend of all the Masters events this year and have picked up smaller titles in places like Barcelona and Estoril.
Nadal's unprecedented sweep of the three clay Masters events in Monte Carlo, Rome and Madrid was backed up by David Ferrer and Fernando Verdasco, whose extremely solid showings included facing Nadal in the finals of Rome and Monte Carlo, respectively. And although Juan Carlos Ferrero has had a modest showing in the spring events, he remains at No. 4 after dominating the Latin-American swing earlier in the year.
The impact of the other great clay nation, Argentina, has been limited because its two top players -- Juan Martin del Potro and David Nalbandian -- have been sidelined with injuries. Juan Monaco also has been hurt but is propped up by some strong Latin-American results, while second strings Juan Ignacio Chela and Eduardo Schwank also have outperformed their rankings. But none has taken the tour by storm.
Unexpectedly, the first non-Spaniard on the list is Ernests Gulbis. The talented but erratic Latvian broke out in Rome, defeating Federer in the second round and reaching the semifinals, where he won one of the only two sets Nadal has lost on clay this season.
Federer and Swiss compatriot Stanislas Wawrinka are tied for sixth on the list, with Federer just about managing to salvage his French Open preparations with a finals appearance in Madrid after going 2-2 in his two previous events. Novak Djokovic also has struggled to find consistent form, and he pulled out of Belgrade and Madrid with allergies.
Meanwhile, Sam Querrey and John Isner have been doing their bit to combat the traditional American futility during this time of year. The Davis Cup teammates reached the final of Rome in doubles and then the singles final in Belgrade a week later, with Querrey winning the title.
Andy Roddick, by contrast, is bringing up the rear after a stomach bug forced him to pull out of Madrid, his only scheduled clay warm-up before the French Open. The other zero-pointers, del Potro and Nikolay Davydenko, haven't played because of wrist-related injuries that also will keep them out of the French Open.
Venus Williams would not have been the name expected at the top of this list when the clay season began, but a title in Acapulco in February and some solid results during the chaos of the past couple of weeks have made this a profitable surface for the elder Williams this season. Sister Serena, the world No. 1, looked strong after ending a long layoff at Rome but remains outside the top 10 here after coming out on the losing end of a couple of three-setters.
Coming in second on this list is Jelena Jankovic, who also hasn't taken any of the big clay crowns but posted a series of quarterfinals and defeated both Williams sisters on her way to the final in Rome. Compatriot Ana Ivanovic is boosted to No. 17 after reaching the semifinal in Rome to stop a slide that has seen her WTA ranking drop to No. 41.
The three surprise winners of the three biggest WTA clay events also made the top five on the strength of those runs. Big-hitting Aravane Rezai won the biggest, Madrid, while Maria Jose Martinez Sanchez and Samantha Stosur charged the net to capture Rome and the green-clay event in Charleston, respectively.
The unretired Justine Henin confirmed that she'll be a French Open contender again after winning in Stuttgart, but then got hit by a virus and hit off the court by Rezai in Madrid, leaving her preparation mixed. Still, she's in better shape than the rest of the Belgians, with Kim Clijsters withdrawing with a foot injury and Yanina Wickmayer racing against time to be ready after an elbow operation.
The Russians are in free fall, with defending French Open champ Svetlana Kuznetsova all the way down at No. 84 in terms of points earned on clay this season and Elena Dementieva not impressing at No. 40. Maria Sharapova, returning from injury, is outside the top 100 after playing and losing her season debut on clay last week in Madrid, although she has taken a wild card into Strasbourg this week and is still alive in the draw.
The young trio of Caroline Wozniacki, Victoria Azarenka and Agnieszka Radwanska also have been low-key. Wozniacki won the small green-clay event in Ponte Vedra Beach, Fla., before injuring her ankle and having little impact subsequently, while Azarenka also appears to have struggled physically.
Kamakshi Tandon is a freelance tennis writer for ESPN.com. Robert Waltz contributed to this story.