ZURICH, Switzerland (AP) — Top-ranked Jelena Jankovic’s 12-match winning streak ended Thursday in a second-round match that left her bruised and bleeding, a 5-7, 6-3, 6-3 loss to Italy’s Flavia Pennetta at the Zurich Open.

Jankovic said she was tired after winning titles the past three weeks in Tokyo; Stuttgart, Germany; and Moscow.

"I didn’t have any gas in the tank," she said. "I am not a machine. Flavia took advantage. She was the better one today."

Olympic champion Vera Zvonareva quit her match because of illness and fifth-seeded Agnieszka Radwanska also lost, leaving only two seeded players in the quarterfinals. Among them is second-seeded Ana Ivanovic, who beat Marion Bartoli of France 6-2, 6-4. Third-seeded Venus Williams advanced Wednesday.

Jankovic fell to the ground at 6-5 and appeared to hurt her left wrist. Still, she broke serve when the Italian double-faulted soon after. The Serb again went down while losing serve in the third game of the second set, and she soon called for a trainer to treat her bleeding right knee.

"I feel like I have been in the war, when I come off the court with bruises and cuts," Jankovic said.

The deciding set went with serve until Pennetta hit a backhand winner to lead 5-3. She had two match points in the next game and converted the first with her third ace.

Jankovic had been 5-0 against the 17th-ranked Pennetta, including a straight-sets win in Moscow last week after the Italian had knocked out Williams. Pennetta said she tried to take more risks and challenge Jankovic.

"Last week I didn’t have a lot of luck and today I was more aggressive," she said.

Jankovic, who has never made it past the second round at the Zurich Open, regained the No. 1 ranking this month. Her final tournament of the season will be the WTA Tour Championship on Nov. 4-9 in Doha, Qatar.

In beating Bartoli, Ivanovic reached her first quarterfinals since winning the French Open four months ago. Since then the former No. 1 has been hampered by thigh and thumb injuries.

"I felt my form beginning to come back a couple of weeks ago, and it’s getting better," Ivanovic said. "I’m just waiting for my consistency."

Zvonareva, seeded fourth, felt sick while trailing Spain’s Anabel Medina Garrigues 6-3, 3-0, and Radwanska fell to Katarina Srebrotnik of Slovenia 2-6, 7-6 (6), 6-3.

Victoria Azarenka of Belarus routed Monica Niculescu of Romania 6-0, 6-0. Niculescu, who had upset seventh-seeded Anna Chakvetadze, failed to convert any of her six break-point chances.