Monte Carlo  - Roger Federer and Davis Cup team-mate Stan Wawrinka advanced into a Swiss showdown at the Monte Carlo Masters on Wednesday as Rafael Nadal made a winning start to another clay-court marathon season.

Newly-married second seed Federer had to fight through as Italian Andreas Seppi saved three match points before exiting 6-4, 6-4 to the 13-time Grand Slam champion.

Federer will next play Wawrinka, who defeated Marcello Vassallo Arguello 2-6, 7-5, 6-2 after two and a half hours. Federer holds a 3-0 record against his compatriot.

Top seed Nadal was broken twice in his 2009 clay debut but had more than enough game to overhaul Argentine Juan Chela 6-2, 6-3.

The Spaniard is again attempting what for anyone else would be the impossible, pointing at five straight titles in Monte Carlo, Barcelona and Roland Garros this spring.

His quest began with success as he ran his record on clay to 134-4 since 2005, with a 22-1 mark in finals on the surface.

The reigning Wimbledon, Paris and Melbourne champion now stands 25-3 this season.

Russian sixth seed Nikolay Davydenko made his return from a heel injury with a win, defeating Croatian Ivo Karlovic, 6-4, 6-3. Spanish seventh seed Fernando Verdasco advanced over German Philip Kohlschreiber 6-3, 6-4.

Argentine David Nalbandian, seeded 12th, made a great escape against Marcello Granollers of Spain 4-6, 6-3, 6-1 while Italy's Fabio Fognini moved into a match with Andy Murray in the third round after dispatching Croatian 14th seed Marin Cilic 6-2, 6-0.

Federer was pleased enough to win his clay opener but always looking for improvement.

"I thought I played okay, I had a good stretch at the end of the first set, beginning of the second. Maybe I could have made it easier for myself in the second.

"I had some opportunities. He hung in there and I didn't play my best. But still happy I came through so good."

Federer and Wawrinka have played twice on the ATP, with Federer winning both but they have never met on clay.

"He's a good friend of mine," said Wawrinka. "It will be nice to play him on the centre court here on clay. I've played him three times already and always lost.

"But those were indoor and hard court. It's gonna be fun to play tomorrow."

Federer was playing his first match since marrying longtime girlfriend Mirka Vanrinec last weekend in his hometown of Basel.

He has lost the last three Monte Carlo finals to Nadal. (dpa)