Stanford, California:Elena Dementieva and Russian compatriot Maria Sharapova won through to the quarterfinals of the WTA's Bank of the West Classic with identical 6-1, 6-2 scorelines on Wednesday.
The third-seeded Dementieva breezed past Russian Maria Kirilenko, while Sharapova had a surprisingly comfortable win over fifth-seeded Nadia Petrova in another all-Russian match.
In other results Wednesday, Slovakia's Daniel Hantuchova ousted seventh-seeded Agnieszka Radwanska of Poland 4-6, 7-6 (6), 6-1 in a tight battle, while Australia's Sam Stosur downed Romania's Monica Niculescu 6-1, 7-5.
Dementieva will face Hantuchova in the quarterfinals, while Sharapova will likely meet second-seeded Venus Williams, whose upcoming second-round opponent is Russian Alla Kudryavtseva.
Sharapova, playing her 17th match since returning from nine months out following shoulder surgery, showed enough form to indicate she would be a test for Williams.
"I was aggressive the whole way through," she said. "I didn't have many letdowns and even when I made unforced errors I stayed with it."
The former world No. 1 player improved to 13-4 on the season and beat Petrova for the seventh time in eight meetings.
Sharapova was pushed to three sets in their most recent match at the French Open.
"This is the easiest score line I've had against her," Sharapova said. "Most of the time we go three sets. She's explosive and always goes for her shot."
Stosur is likely to face top-seeded Serena Williams in the last eight. Serena will meet Hungary's Melinda Czink in the second round.
Britain's Anne Keothavong, who left her doubles match after crashing into a fence on Tuesday night, is out for the rest of the season. Tests on Wednesday morning revealed a severe left knee sprain.