Roger Federer, Rafael Nadal and Sony Ericsson Open: Day 6 Matches to Watch

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Four of the most recognizable names in tennis—Roger Federer, Kim Clijsters, Vera Zvonareva and Rafael Nadal—are in action today, as the men complete the third round and the women begin filling in quarterfinal spots.

Here are the Day 6 matches to watch.

Roger Federer (SUI) vs. Juan Monaco (ARG)

For having fairly lengthy careers, somehow these two have matched up only one time, that coming four years ago in Hamburg. Monaco won his first match to get back to .500 (7-7), while Federer is off to a 19-3 start The winner likely gets Mikhail Youzhny in the fourth round. Fed hasn't won here or made the final since 2006.

Rafael Nadal (ESP) vs. Feliciano Lopez (ESP)

Lopez is among the rare group who actually beat Nadal last summer, doing so in the quarterfinals at London just before Nadal captured Wimbledon. Overall, Rafa is 6-2 against his fellow left-handed Spaniard.

Alexandr Dolgopolov (UKR) vs. Jo-Wilfried Tsonga (FRA)

It's the highly anticipated rematch of Dolgopolov's coming-out party at the Australian Open in January. Down two sets to one, he blew out Tsonga 6-1, 6-1 in the final two sets and wound up in the quarterfinals. He's carried the momentum forward and is 15-7 on the year, ranked 23rd in the world, just seven spots behind the 11-5 Tsonga. The winner likely sees Nadal in the fourth round.

Samantha Stosur (AUS) vs. Maria Sharapova (RUS)

Sharapova has owned Stosur with six wins in six tries during her career. Couple that with last week's semifinal appearance at Indian Wells, and things are looking up for the Russian former No. 1. She reached the finals here in 2005 and 2006, but this is her first time to play here since 2007—meaning the points she picks up are all freebies.

Stosur is finally over .500 for the year (9-7) and has finally started to play better with a pair of two-set sweeps.

Marion Bartoli (FRA) vs. Vera Zvonareva (RUS)

The resident tour "genius" has proven that last week's trip to the Indian Wells final was no fluke, rushing through the first three rounds here. Meanwhile, Zvonareva needed three sets to beat Dinara Safina and a first-set tiebreak to get ahead of Jarmila Groth. She's just not playing with the same killer instinct we saw at times during the majors of 2010.

Early in their careers, Zvonareva took eight of nine matches from Bartoli, but the Frenchwoman won their last matchup, at the 2009 Beijing quarterfinals.

Ana Ivanovic (SRB) vs. Kim Clijsters (BEL)

Two former No. 1s hook up, one taking that top spot quite recently. Clijsters needed three sets to reach this round, as did Ivanovic. Clijsters leads their head-to-head series 3-0 with two wins last season—at the US Open and Cincinnati.

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