Stuttgart, Germany -- (Sports Network) - U.S. Open runner-up Jelena Jankovic, French Open and Olympic runner-up Dinara Safina and Wimbledon champion Venus Williams were a trio of second-round winners Thursday at the $650,000 Porsche Tennis Grand Prix.

The second-seeded Jankovic, who will supplant Serena Williams atop the world rankings on Monday, blew past Ukrainian Alona Bondarenko 6-2, 6-0 on the indoor hardcourts at Porsche Arena. The steady Jankovic was last week's hardcourt champion in Beijing.

Jankovic's quarterfinal opponent here on Friday will be seventh-seeded Russian Vera Zvonareva, who zipped past France's Marion Bartoli 6-2, 6-0 on Day 4. Zvonareva captured an Olympic bronze medal in Beijing back in August.

Meanwhile, the third-seeded Safina, who titled at a WTA Tour event in Beijing two weeks ago and captured a silver medal at the Beijing Games, got past Bulgarian qualifier Tsvetana Pironkova 6-1, 7-6 (8-6), while a sixth-seeded Venus waltzed past Ukrainian qualifier Kateryna Bondarenko 6-4, 6-2.

Russian Nadia Petrova cooled off Swiss lefthander Patty Schnyder 6-4, 6-1, as Schnyder was riding a five-match winning streak, including a title in Bali last month.

Friday's other quarters will pit Safina against Venus, fourth-seeded Russian Elena Dementieva versus Belarusian Victoria Azarenka and Chinese Na Li against Petrova. Dementieva is the reigning Olympic gold medalist. Li shocked a top-ranked Serena here on Wednesday.

The 2008 Stuttgart titlist will take home $100,000.