Federer has twice beaten Nadal on clay
Defending champion Roger Federer got back to winning ways with a 6-2 7-6 (7-4) victory over Germany's Benjamin Becker at the Madrid Open.
Top seed Federer broke Becker's serve twice in the first set and, after two match points slipped by, the Swiss wrapped things up in the tie-break.
Federer had lost his opening clay-court match of the year in Rome last month and then lost in the Estoril semis.
In the women's draw, Caroline Wozniacki lost 6-2 6-3 to Alona Bondarenko.
Federer, 28, has made the Madrid final in three of the past four years, also winning in 2006, but has not claimed a title since lifting his 16th Grand Slam title at the Australian Open in January.
When you've twisted you're ankle a few times, as I have, you need your confidence back, especially on clay
"I'm happy with the way I reacted after all that happened in the last few weeks and months," said Federer.
"The moment the match started, I felt great. I was hitting the ball fine and I think the centre court here just feels right to me - I've never lost on it, so that gives me confidence and I think it showed today in my game."
Spanish sixth seed Fernando Verdasco beat big-serving Ivo Karlovic of Croatia 7-6 (7-5) 6-3 in their first meeting on clay.
Argentine Juan Ignacio Chela booked a meeting with Andy Murray having barely broken sweat after first-round opponent Pablo Cuevas retired during their match with just two games played.
Meanwhile, Latvia's Ernests Gulbis beat Estoril Open champion Albert Montanes of Spain 7-5 6-1.
Cypriot Marcos Baghdatis recorded a 6-3 6-4 win over Marco Chiudinelli and 15th seed Stanislas Wawrinka beat Spain's Marcel Granollers 6-4 6-4 to set up a clash with fellow Swiss Federer.
Argentina's David Nalbandian, who won the event in 2007, was scheduled to meet Czech 11th seed Tomas Berdych in the first round but both players pulled out injured.
In the women's competition, second seed Wozniacki said she was still suffering with an ankle injury after she lost to Bondarenko but expected to be fit for the French Open in two weeks' time.
"When you've twisted you're ankle a few times, as I have, you need your confidence back, especially on clay," said the 19-year-old Dane.
"It's uneven, and you need to be confident that you really can go out there and slide really wide."
There was another shock as Alexandra Dulgheru of Romania beat sixth seeded Elena Dementieva 6-1 3-6 7-5.
Swiss veteran Patty Schnyder fought back from a set down to beat ninth seed Agnieszka Radwanska 3-6 6-4 6-4, while Anabel Medina Garrigues eased past number 12 Marion Bartoli 6-2 6-0.
Number 14 seed Flavia Pennetta suffered a 7-6 6-3 defeat to Andrea Petkovic.