Wins have been hard to come by for Petkovic since returning from four months out with a serious ankle injury, but there were plenty of encouraging signs against Jankovic.
Most heartening for Petkovic will have been her performance at the end of a tight opening set, where she fended off a handful of break points at 4-4 before claiming the decisive break herself a few games later. From then on it was one-way traffic, Petkovic dropping just seven more points as she raced into the quarterfinals, 75 60.
"The first set was the key moment," Petkovic said. "It was always going to be a turning point because it was such an intense first set. We were pushing each other so hard and afterwards Jelena's level dropped just a little bit and I managed to capitalize."
"I lost to Ksenia at Wimbledon in 2011," Petkovic added. "She played a great match - I played a terrible match - but she didn't make it easy to play my best tennis. I'm very excited to play her again and try and make a few things work a little better this time."
Jankovic and Cirstea were not the only seeds failing to make it beyond the second round, though; No.2 seed Julia Goerges, a finalist last week in Linz, lost to Monica Niculescu, 64 62, while No.9 seed Mona Barthel battled bravely before eventually going down to Venus Williams, 76(4) 64.
"At 4-0 in the first set, I thought I had the set. Then I started to miss a few shots and she made a few more and the lead was gone," Williams said. "I made sure I stayed positive, though, and I think this helped me get the set in the end.
"I had a lead again in the second, but she was so tough and never gave up. The courts are playing a bit slow and Mona has great defense, so the ball just kept coming back and coming back. She made it so tough but I had to be patient and I'm happy with the result."