GSTAAD, Switzerland -- Third-seeded Jiri Novak recovered from a weak first set Wednesday to defeat France's Paul-Henri Mathieu 1-6, 6-2, 6-3 and advance to the Swiss Open quarterfinals.

Novak, a Czech who won this title in 2001, will next play Juan Ignacio Chela. The fifth-seeded Argentine edged Spain's Feliciano Lopez 6-4, 6-7 (2), 7-6 (3).

"This was an important win for me and it wasn't easy,'' said Novak, who is seeking his first title of the season.

Back on clay after losing in the opening round of Wimbledon, fourth-seeded Gaston Gaudio of Argentina downed Lars Burgsmueller of Germany 4-6, 6-2, 6-4.

In the quarters, Gaudio will meet Stefan Koubek of Austria, who routed Anthony Dupuis of France 6-1, 6-2. Koubek is trying to win his second title this season.

Novak reached the third round at Wimbledon for the first time in eight years. He has played well on clay this year, making the fourth round of the French Open.

This season, Chela has reached the semifinals in Chennai, India, and the quarterfinals in Monte Carlo and Buenos Aires.

Gaudio lost to Alex Corretja in last year's Swiss Open final. Gaudio reached the semifinals of three tournaments this season, all on clay.