French Open 2012: Which Stars Regressed This Tourney?

Julian Finney/Getty Images

The 2012 French Open has seen some prolific play from clay masters such as Rafael Nadal and David Ferrer, but it has also seen some of the sports' biggest stars regress.

Several of tennis' most prominent players were tripped up at Roland Garros, including a few notable Americans in both the men's and women's draws.

For some of the athletes, the regression isn't shocking. But for others, the lackluster Parisian performance is a significant letdown.

Here are five tennis stars who regressed during this year's tournament.

Andy Roddick

Julian Finney/Getty Images

The French Open hasn't historically been Andy Roddick's best tournament, but a first-round exit is still disheartening.

A-Rod's four-set defeat at the hands of Nicolas Mahut sent him packing early this year.

Mahut outplayed Roddick at the net, had a more effective serve and made quick work of the American on most of the short rallies.

Roddick's 2012 went from bad to worse with this discouraging loss.

Caroline Wozniacki

Julian Finney/Getty Images

Once the envy of the tennis world, Caroline Wozniacki seems to have lost the touch that kept her atop the rankings for much of 2010 and 2011.

2012 hasn't been kind to the Danish star, and the French Open was a continuation of the disappointment.

Her third-round loss to Estonia's Kaia Kanepi squashed any chance for her to reach or surpass the quarterfinals, which would have been her best career finish at Roland Garros.

Wozniacki's pattern of underachieving at Grand Slam events gives reason to wonder whether she'll ever win a major.

John Isner

Al Bello/Getty Images

Tenth-seeded John Isner failed to improve at Roland Garros, as his second-round loss to Paul-Henri Mathieu was the longest match ever in French Open history.

Isner's size, menacing serve and lack of mobility have always yielded awkwardly lopsided statistics, and this match was no different.

The towering American torched Mathieu for 41 aces, but he lost the match largely because of his 98 unforced errors. That's right, 98.

We'll see if Isner can pick himself up after slumping the past few weeks. He hasn't been on top of his game since toppling Jo-Wilfried Tsonga in the Davis Cup.

Serena Williams

Mike Hewitt/Getty Images

Since her championship at the Mutua Madrilena Madrid Open in early May, things have gone downhill for Serena Williams.

Her semifinal loss in Italy was followed up by a disastrous first-round upset at Roland Garros, where Virginie Razzano stunned the fifth-seeded American.

Williams' play was far from tidy, as she made plenty of mistakes and converted just 25 percent of her break-point chances.

It remains to be seen whether this regression is only temporary, or just a clay-caused setback.

Roger Federer

Clive Brunskill/Getty Images

Roger Federer's 2012 has been a roller-coaster ride thus far, including titles at Dubai and the PNB Paribas Open and early-round losses to John Isner at the Davis Cup and Andy Roddick at the Sony Ericsson Open.

Reaching the semifinals at Roland Garros isn't a huge disappointment, but the Swiss maestro's struggles signaled the continued regression of his career.

His second-, third- and fourth-round opponents all gave him some trouble, and Juan Martin Del Potro nearly knocked him off in the quarterfinals.

It was Novak Djokovic's three-set sweep of Federer that exposed how far he is from the elite.