LUXEMBOURG (AP) -- Venus Williams beat top-seeded Roberta Vinci of Italy 7-6 (2), 6-4 on Friday to reach the semifinals of the Luxembourg Open.

Playing in her first tournament since the U.S. Open, Williams will face Andrea Petkovic of Germany, who defeated Ksenia Pervak of Kazakhstan, 6-3, 6-2.

Williams had struggled with a back problem at the U.S. Open.

In the bottom half of the draw, Daniela Hantuchova of Slovakia beat Lourdes Dominguez Lino of Spain, 7-5, 6-0 to set up a semifinal against Monica Niculescu of Romania, who defeated Lucie Hradecka of the Czech Republic, 6-0, 6-4.

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