NEW HAVEN (AFP) - Defending champion Caroline Wozniacki headed indoors Friday to book a return to the women's final of the Pilot Pen hardcourt tennis tournament, last tuneup for the US Open. Persistent rain prompted WTA officials to move their matches indoors at the event, and second-seeded Wozniacki, after waiting all day for a chance to play, gave herself at a chance at a repeat title with a 6-4, 6-1 victory over third-seeded Italian Flavia Penetta. "I was so focused on the match, I didn't really think too much about the other things," Denmark's Wozniacki said. "I like to play indoors, so I didn't mind playing indoors. The most important thing is that I won. All the other things really doesn't matter." She'll play Russia's Elena Vesnina, who ousted eighth-seeded French veteran Amelie Mauresmo 5-7, 6-1, 6-2. Wozniacki handed Penetta just her third defeat in her last 21 matches, a run that included titles in Palermo and Los Angeles. "I didn't serve very well today," Pennetta said. "It's a little bit different play indoor to outdoor. The ball was always like really near my head. I didn't jump a lot today. I think she played a great match. She was very focused and very aggressive from the beginning. I had my chances, but I didn't make it." Organizers elected to postpone the men's semi-finals, hoping to get them in on Saturday. American Sam Querrey, who toppled top-seeded Nikolay Davydenko in the quarters, is to take on Argentina's Jose Acasuso, while second-seeded Spaniard Fernando Verdasco is to play seventh-seeded Russian Igor Andreev. Officials hope to play the men's semi-finals in the morning, and both finals on Saturday evening. However, Saturday's forecast is poor, as tropical storm Danny is expected to contribute to heavy rain and high winds. The tournament is scheduled to end on Saturday, giving players a chance to rest before the start of the US Open - the last Grand Slam of the year - on Monday. But if necessary matches could be played on Sunday, organizers said.