Serena Williams tops Petkovic in Stanford semis

STANFORD, Calif. (AP) Serena Williams reached her fourth final of the season by taking the last eight games to beat Andrea Petkovic 7-5, 6-0 on Saturday in the Bank of the West Classic.

The top-seeded and top-ranked Williams is 3-0 in finals so far in 2014, winning titles at Brisbane, Miami and Rome.

The tournament is Williams' first since she tried to play through a viral infection that caused her to lose equilibrium during a doubles match with sister Venus at Wimbledon.

Against the ninth-ranked Petkovic, Williams wasted four break points in the final game of the first set before eventually converting her fifth.

In Sunday's final at the hard-court tournament, Williams will face third-seeded Angelique Kerber, a 4-6, 7-6 (4), 6-2 winner over Varvara Lepchenko.

Petkovic was trying to become the ninth player - and first since 2010 - to beat both Venus and Serena Williams in one tournament. Petkovic eliminated Venus on Friday.