MASON, Ohio (AP) — Top-ranked Novak Djokovic tumbled out of the Western & Southern Open on Thursday, while second-seeded Roger Federer narrowly avoided an upset in the round of 16.
Tommy Robredo beat Djokovic, 7-6 (6), 7-5 before Federer escaped with a 6-4, 4-6, 6-3 victory over Gael Monfils in the night session.
Andy Murray also came close to elimination but saved two match points in a 6-7 (3), 6-4, 7-6 (2) win over 11th-seeded John Isner to reach the quarterfinals. Milos Raonic and Fabio Fognini also advanced.
On the women's side, top-seeded Serena Williams continued her pursuit of her first title in the Cincinnati-area tournament with a 6-2, 6-2 victory over Flavia Pennetta.
Simona Halep also reached the quarterfinals, where she will meet Maria Sharapova. Agnieszka Radwanska, Jelena Jankovic and Ana Ivanovic also progressed.
Robredo's victory was the second time in his career he had beaten the world's top-ranked player. The first occasion was way back in 2003 when he defeated Lleyton Hewitt in the 2003 French Open.
"When I finish my career, and when I will be sitting at home and talking with friends, I will remember days like this," Robredo said.
Djokovic, who has never won the Cincinnati-area event, dropped the first set after fighting back from a 6-3 deficit in the tiebreaker. Robredo took the set with an ace that Djokovic challenged. The replay showed the ball caught the slimmest sliver of the line.
Robredo was denied on two match points before completing the victory with a smash on Djokovic's short lob.
"It's disappointing that I'm finishing Cincinnati again with a tough loss, but it's the sport," said Djokovic, who lost in the third round at Toronto last week. "I didn't play well in Toronto, didn't play well here. Hopefully, it's going to be different in New York (at the U.S. Open)."
Federer had trouble shaking off a persistent Monfils in his 6-4, 4-6, 6-3 victory.
"There was some frustration, but that's what Gael does to you," Federer said. "I felt like I missed some opportunities in the second set to close him out, but that's a credit to him. He hung in there."
Murray, who is coming off an injury-interrupted season, would have been expecting a long match against the towering Isner because the American is rarely broken on service and won before a standing-room-only crowd.
"I had lost a few close matches — matches like that — over the last few months, so it was important for me to come through," Murray said, a two-time W&S champion. "It was completely packed crowd from the first point right until the end, as well. So it was a really good atmosphere to get ready for the rest of the tournament, but also the U.S. Open, as well."
Isner, who lost to Rafael Nadal in last year's final, had two chances to win the match with a 6-5 lead in the third set, but Murray salvaged both points before taking control with a mini-break for a 3-1 lead in the tiebreaker.
Stan Wawrinka shook off losing the first set to roll through the next two and advance with a 3-6, 6-0, 6-1 win over Marin Cilic. Wawrinka, the Australian Open champion, will meet unseeded Julien Benneteau in the quarterfinals. Benneteau eliminated Jerzy Janowicz 7-5, 6-1. Fabio Fognini also needed three sets to get past Yen-hsun Lu, 3-6, 6-3, 6-3, and Milos Ranoic held off wild-card Steve Johnson 6-7 (6), 6-3, 7-6 (4).
David Ferrer completed the quarterfinal bracket with a 7-5, 6-0 win over Mikhail Youzhny.
In women's play, top-seeded Williams broke serve in the opening game and went on to comfortably beat Pennetta 6-2, 6-2.
"I got the early break, and I didn't let go," she said. "That's what I wanted to do. She tried to come back, I wanted to stay focused."
Halep also reached the quarterfinals with a 6-4, 7-5 win over Lucie Safarova, but 15th-seeded Carla Suarez Navarro was upset by unseeded Elina Svitolina, 4-6, 6-4, 6-4.
Halep and Sharapova will meet in the quarterfinals — a reprise of the French Open final won by Sharapova. The fifth seed advanced with a 6-4, 7-6 (2) win over Anastasia Pavlyuchenkova. Jankovic also moved on with a 7-6 (4), 6-4 victory over Sloane Stephens, and Ivanovic advanced with a 6-2, 2-6, 6-3 win over Svetlana Kuznetsova. Agnieszka Radwanska routed Sabine Lisicki 6-1, 6-1.
Caroline Wozniacki reached the quarterfinals for the second straight time and third overall with a 7-5, 6-2 victory over Angelique Kerber.