Estoril, Portugal - Roger Federer stayed focused amid two annoying rain interruptions to reach the semi-finals of the Estoril Open on Friday 6-4, 6-1 over an upset-minded Portuguese challenger.

The win against 146th-ranked Frederico Gil propelled Federer into the weekend at his opening event on spring clay while working on a trial basis with past Spanish master Jose Higueras.

The world number one will await an opponent from Czech Jiri Vanek and German Denis Gremelmayr, hoping that the afternoon dry spell would last through their encounter.

Gil had to finish off a held-over, match form Friday when rain intervened. He booked his place against Federer over compatriot Joao Sousa, 7-6 (7-5), 6-2.

Federer and Gil were forced to the clubhouse for more than 30 minutes midway through the opening set and for almost that long at the third game of the second.

Federer won the first set after giving up one break but closing with another. But the improbable conditions also sent him crashing to a service break down as he began the second set.

The top seed got that one back and returned after the second interruption with all guns firing as he swept to the victory, wrapping things up with his fifth ace.

Major rival and second seed Nikolay Davydenko was playing for his semi-final spot later against French seventh seed Marc Gicquel, ranked 55th.

Russia's Davydenko was taking a nine-match win streak into the contest.

Davydenko owns a 2-0 record against Gicquel, whose only win over a Top-ten opponent came at Lyon in 2007 against Spain's Tommy Robredo.

On the women's side, second seed Maria Kirilenko of Russia advanced into the semis against Italian Tathiana Garbin 6-0, 6-1.

Czech Iveta Benesova defeated French eighth seed Camille Pin 3-6, 6-2, 6-3. (dpa)