World number one Roger Federer recovered from one set down to beat unseeded German Denis Gremelmayr 2-6, 7-5, 6-1 on Saturday to reach his first final of the year at the Estoril Open.

The 26-year-old Swiss struggled to counter Gremelmayr's powerful baseline game but pulled clear with a series of aces in the third set to face either Nikolay Davydenko of Russia or France's Florent Serra in Sunday's final.

"I think Denis played a fantastic match," Federer, who is recovering from his worst start to a season since 2000, told reporters.

"I read reports that I struggled yesterday and I only lost five games. Today was much closer. But I'm used to it. It's almost bigger news when I lose than when I win. I guess that's a nice problem to have."

Federer hit 10 aces in windy conditions to move closer to claiming his 54th ATP title.

In the women's final, second-seeded Russian Maria Kirilenko will be seeking her third title against 2004 finalist Iveta Benesova of the Czech Republic.

Benesova defeated Estonia's Maret Ani 6-2, 6-1 while Kirilenko beat Klara Zakopalova of Czech Republic 2-6, 6-3, 7-5 in Saturday's semi-finals.