(Reuters) - Top seed Serena Williams came from a set down to book her place in the Stanford Classic semi-finals with a hard-earned 2-6 6-3 7-5 win against fifth-seeded Serb Ana Ivanovic on Friday.
Serena, whose sister Venus was beaten in three sets by Germany's Andrea Petkovic earlier in the day, initially struggled on a fast playing surface but gradually found her range to seal victory in just under two hours.
