Safina Safely Through to Quarters in Stuttgart

World number three Dinara Safina of Russia beat Bulgarian Tsvetana Pironkova 6-1 7-6 in the second round of the Stuttgart Grand Prix on Thursday to set up a potential quarter-final against Venus Williams.

The powerful Safina, playing her first match at the indoor tournament after receiving a first-round bye, raced through the first set but faced much stiffer resistance from the 21-year-old qualifier in the second.

Wimbledon champion Williams, seeded six, plays Kateryna Bondarenko of Ukraine later on Thursday.

Earlier, Safina's compatriot Nadia Petrova beat Patty Schnyder of Switzerland 6-4 6-1.

Petrova will play China's Li Na, a surprise winner over world number one and top seed Serena Williams on Wednesday, for a place in the semi-finals.

Vera Zvonareva, another Russian, had a comfortable victory over Marion Bartoli of France on Thursday, winning 6-2 6-0.

The seventh seed will face either Serbian world number two Jelena Jankovic or Ukrainian Alona Bondarenko in Friday's quarter-finals.

Russian world number four Elena Dementieva takes on Victoria Azarenka of Belarus in Friday's remaining quarter-final.