STANFORD, Calif. — Maria Sharapova has needed just over an hour to beat 10th-ranked and fifth-seeded Nadia Petrova, 6-1, 6-2, in a second round match of the $700,000 WTA Premier Bank of the West Classic.

The former world No. 1 player improved to 13-4 on the season and beat Petrova on Wednesday for the seventh time in eight meetings.
In another second round match, Samantha Stosur downed Monica Niculescu, 6-1, 7-5.
Britain’s Anne Keothavong, who left her doubles match after crashing into a fence on Tuesday night, is out for the remainder of the season. Tests on Wednesday morning revealed a severe left knee sprain.