OEIRAS, Portugal — Roger Federer rallied from a set down to defeat Olivier Rochus of Belgium 4-6, 6-3, 6-2 today in the first round of the clay-court Estoril Open.

The top-ranked Swiss player had 17 aces, but also many unforced errors, against the 80th-ranked Belgian. It was Federer's first match since he started working with coach Jose Higueras, a clay-court specialist.

Federer is struggling through his worst start to a season since 2000 — the last time he went four tournaments without a victory. Only two Grand Slam titles short of tying Pete Sampras' record of 14, Federer still needs to win the French Open to complete a career Grand Slam.

Second-seeded Nikolay Davydenko also made a shaky start against Jurgen Melzer, but recovered to win 6-3, 6-1. Davydenko, coming off a victory at the Sony Ericsson Open, lost his first service game and trailed 2-0 before breaking his opponent's serve three times in the first set.

The Russian won the Estoril Open title in 2003 and lost in the final two years ago.

Third-seeded Ivo Karlovic withdrew because of an injury while trailing 6-4, 1-0 against Rui Machado, and eighth-seeded Michael Berrer defeated Gastao Elias 6-4, 7-5.

In the women's event, top-seeded Flavia Pennetta dropped the opening set against Yvonne Meusburger before recovering to win 4-6, 6-0, 6-2.

Second-seeded Maria Kirilenko also struggled before beating Stefanie Vogele, and fifth-seeded Tathiana Garbin knocked out Yuliya Beygelzimer.