Sharapova is currently ranked outside the top 50 in the world
Russia's Maria Sharapova continued her return from injury with a second-round win over third seed Victoria Azarenka at the Los Angeles Championships.
The former world number one, 22, who is returning from shoulder surgery, battled back from a set down to beat the Belarusian 6-7 (4-7) 6-4 6-2.
Current number one Dinara Safina eased into the third round with a 6-2 6-4 win over Slovakia's Daniela Hantuchova.
Sorana-Mihaela Cirstea beat fourth seed Caroline Wozniacki 1-6 6-4 7-6 (7-5).
Safina's straightforward win guarantees her enough points for a berth in the season-ending WTA Tour Championships in Qatar.
The Russian said: "I didn't do anything spectacular. We play the same way, so it depends on who's going to take charge of the points, and at the crucial times I was more aggressive
Sharapova was made to work a little harder by Azarenka, but she came through to set up a third round match with Ukraine's Alona Bondarenko.
"I knew I was going to have to dig deep and try to find ways," said Sharapova. "I'm pretty happy with the way I was able to hang in with her and really step up when I had to. That was the difference between us."
Poland's Urszula Radwanska upset seventh seed Dominika Cibulkova 6-4 6-7 (6-8) 6-4 and will play China's Li Na, who defeated Canada's Alexandra Wozniak 4-6 6-4 6-2.
Other winners included Russia's number five seed Nadia Petrova, who beat Israel's Shahar Peer 6-4 2-6 6-3, and Polish eighth seed Agnieszka Radwanska, who eliminated Japan's Ai Sugiyama 6-2 6-1.
Australia's Samantha Stosur set up a third-round meeting with Serbian eighth seed Ana Ivanovic by beating Russia's Maria Kirilenko 6-2 6-4.