Four weeks into the European clay-court season and a few days from Roland Garros, it's time to assess the clay-court abilities of the top contenders for the French Open title. Novak Djokovic has proved he can beat Rafael Nadal. Juan Martin del Potro is back in form -- if he's healthy. And Milos Raonic's big, fast game is a legitimate threat even on a slow surface.
One thing is certain: The one-size-fits-all ATP rankings aren't sufficient to handicap players ahead of the French. Using my surface-specific system (see sidebar), we can get a better sense of who is dangerous on clay and who will head home before Week 2. Let's take a look at the rankings:
1. Rafael Nadal
A recent string of losses to Djokovic notwithstanding, Nadal is still the player to beat on clay. The Serb snapped Nadal's 37-match win streak in Madrid and then beat him in the Rome final. Nadal also recently dropped sets to both Roger Federer and Andy Murray, but the reigning French Open champion might be more dangerous than ever, looking for ways to tighten up his game, playing like he has something to prove.
2. Novak Djokovic
The Serb's game is seemingly built for clay, so it's not a huge surprise that he has vastly improved on his 2010 results by winning every match he has played on the surface this year. He dropped sets to both David Ferrer and Thomaz Bellucci in Madrid, suggesting he hasn't reached the level of infallibility he has shown on hard courts this year. But his two convincing wins over Nadal on clay suggest the gap is not nearly as wide as it once was.
3. Juan Martin del Potro
Before he withdrew with a hip injury in Madrid, del Potro was a perfect 7-0 on the surface, with wins over Robin Soderling, Fernando Verdasco and Marin Cilic. The last time he played Roland Garros, as a 20-year-old in 2009, he reached the semis and pushed Federer to a fifth set. If he's healthy enough to play the French, he will be the dark horse to watch.
4. Roger Federer
In the first set of the Madrid semifinal against Nadal, Federer looked like the best player in the world, attacking from all over the court, even landing winners with his much-maligned one-handed backhand. In the next two sets, he won only four games. That is 2011 Roger in miniature: offering glimpses of past brilliance, ultimately out of the running. That was validated in a tight, three-set loss to Richard Gasquet in Rome. He's still a safe bet to reach the French Open semis, but he's not getting any further.
5. David Ferrer
The Spaniard has always been a scrapper, and he has taken it to a new level this season. Against everyone except Djokovic and Nadal, Ferrer has been nearly flawless on clay, defeating Feliciano Lopez, Nicolas Almagro and Jurgen Melzer (twice) in straight sets. In both of his recent finals against Nadal, he broke Rafa at least twice, suggesting that on a day when everything clicks, he could beat the best in the world.
6. Andy Murray
Murray had Djokovic -- and the streak -- on the ropes in Rome. He looked to be the stronger player, although he succumbed in a third-set tiebreaker. Murray also took a set off Nadal in the Monte Carlo semifinals. Like Federer, Murray found it impossible to sustain that level of play for the entire match. Still, it was a step forward for the Scotsman, which should make him a force this time of year.
7. Robin Soderling
It's been a rough year for the Swede, struggling with a foot injury and losing to the likes of Ivan Dodig. Nonetheless, this is a man who reached the final of Roland Garros last year, knocking out Federer in the process. It's also worth remembering that he had a rough time leading up to last year's French as well, losing his first match in both Madrid and Nice.
8. Jurgen Melzer
There's a big drop-off in these rankings between 4-7 and 8-10, and the only thing keeping Melzer in the top 10 is his clinical victory over Federer in Monte Carlo a few weeks ago. Like Soderling, the lefty can't be counted out, having beaten both Ferrer and Djokovic in last year's French. Then again, he's lost to Ferrer twice on clay this season.
Berdych reached the semis at Roland Garros last year but hasn't made an impression on clay since. His game is better suited to fast courts, as evidenced by his lackluster loss in Monte Carlo to Ivan Ljubicic. He did put up a good fight against Gasquet in Rome, losing in three sets. Still, he's no one-dimensional player, and he'll probably be around for the second week in Paris.
10. Fernando Verdasco
This season, the Spaniard has been a riddle, wrapped in a mystery, inside a Cosmo model. Last year, he reached three clay-court finals, beating Djokovic and Ferrer each. More recently, he has failed to win a match in three of his past four clay-court events, including an embarrassing defeat at the hands of Yen-Hsun Lu. The game is there, but the mind could be anywhere.
The next 10:
Jeff Sackmann covers college baseball for ESPN Insider. With Kent Bonham, he co-founded College Splits, which provides amateur baseball data and analysis for MLB teams. You can follow him on Twitter here.