World number one Rafael Nadal will face Juan Martin Del Potro in the third round of the Madrid Open.
All the leading men's seeds claimed victories, albeit with varying degrees of difficulty, with Nadal seeing off Cypriot Marcos Baghdatis 6-1 6-3 while in-form second seed Novak Djokovic made it 28 wins out of 28 this year after defeating South African Kevin Anderson 6-3 6-4.Fifth seed Robin Soderling also won fairly comfortably with a 6-3 6-3 triumph over Colombian Santiago Giraldo, but Roger Federer and Andy Murray needed to dig deeper for their victories.
Murray, the fourth seed, eventually claimed his sixth win in seven meetings with Gilles Simon after beating the Frenchman 6-4 3-6 6-0, while Federer had a titanic battle with local boy Feliciano Lopez before squeezing through 7-6 (15/13) 6-7 (1/7) 7-6 (7/5) in a match that lasted three minutes short of three hours.
Federer, who saved a match point against Lopez, said: "I thought he (Lopez) played well, you could see he's been playing a lot of matches and he's confident and I'm really relieved to have come through because it wasn't easy at all."
Federer will now face Xavier Malisse while Djokovic takes on Guillermo Garcia-Lopez as the Serbian seeks his sixth successive title of 2011. Murray meets Thomaz Bellucci next, and Soderling's opponent will be Jo-Wilfried Tsonga.
There is a little doubt which is the most intriguing third-round match though, with clay court king Nadal taking on 2009 US Open champion Del Potro in a match that seems more suited to the latter stages of the competition.
Del Potro, the former world number four who dropped to to 484th place after playing just three tournaments in 2010 having undergone wrist surgery, climbed back up to 32nd with two victories already this year, the latest in Estoril at the weekend.
The Argentinian, who thumped Marin Cilic 6-3 6-0, said of the game: "Obviously it will be one of the most difficult matches here on clay that there can be.
"I've never been capable of beating him on clay and let's see if it's tomorrow, but let me repeat that it's against the number one in the world and he's the best without a doubt on this type of surface."
Nadal, who took his winning streak on clay to 35 successive matches with his win over Baghdatis, said: "You know that normally you wouldn't play against him (Del Potro) so early. Normally you would play against him in the quarters or semis, at least.
"This is one of the errors of the ATP rankings: when you get injured you fall down the rankings quite a lot, which is quite unfair for a player like Del Potro who has more than shown that his ranking isn't what it is now.
"So I think it's bad news for him, it's bad news for me, bad news for the tournament to have the match now and not in the quarter-finals or semi-finals because one of us is going to be out."
Also going through was seventh seed Tomas Berdych, who defeated Marcel Granollers 6-4 6-0, while the only seeded casualty was number eight Jurgen Melzer, who lost 7-6 (10/8) 6-3 to Spaniard Daniel Gimeno-Traver.
Whilst the majority of the seeds in the men's event had a good day, it was a different story in the women's with top seven players Vera Zvonareva, Jelena Jankovic and Maria Sharapova all tumbling out.
Second seed Zvonareva, who could have climbed up to second in the world rankings by reaching the final with current number two Kim Clijsters sidelined with injury, lost her third-round match to 16th seed Petra Kvitova of the Czech Republic 6-1 6-4.
Serbian Jankovic, the seventh seed, also bid farewell after losing her second-round match 6-4 4-6 7-5 to Lucie Safarova of the Czech Republic, while number eight Sharapova was knocked out late on after losing 7-5 6-4 to Dominika Cibulkova in the third round.
Sixth seed Na Li of China had a much easier time of it, though, as she defeated Iveta Benesova 6-1 6-4 in the second round.
