INDIAN WELLS, Calif. — Top-ranked Caroline Wozniacki advanced to the BNP Paribas Open semifinals when Victoria Azarenka retired with a hip injury while trailing 3-0 in the first set Thursday.
On the men’s side, 25th-seeded Tommy Robredo withdrew before his quarterfinal against Juan Martin del Potro because of a strained left abductor muscle he injured in his match a day earlier.
Wozniacki next plays Maria Sharapova, who outlasted Peng Shuai 6-2, 5-7, 6-3 to reach her first semifinal of the year after missing the last five weeks with a viral illness.
Wozniacki broke for a 2-0 lead after the first two games went to deuce. She was leading 30-0 in the third game when Azarenka called for a trainer.
Azarenka lay on the court and had her upper left thigh massaged before she took a 10-minute medical timeout. While she was gone, Wozniacki went behind a wall on court to stretch her legs and talk to her coach.
Azarenka returned with her left thigh wrapped. Wozniacki resumed serving and won the next two points to go up 3-0 before Azarenka signaled she was done.
They hugged at the net and Wozniacki patted Azarenka on the shoulder.
“Victoria is one of my best friends on the tour, and to see her in pain on the court and to see her get injured was not nice for sure,” Wozniacki said.
During their match, a Japanese flag was tied to the chair umpire’s tower and written on it in black marker were the words, ‘Our thoughts are with you! Caroline and Victoria.’ After Azarenka left, Wozniacki untied it and held it up in tribute to the victims of the recent earthquake and tsunami.
“It’s just devastating to see what’s going on in Japan,” the Dane said. “We just wanted to show that we’re thinking about them over there.”
Wozniacki had asked her manager to locate a Japanese flag. He finally found one, two hours from Indian Wells.
“I said, ‘You better take your car and drive over there and get that flag to me,’” she said, smiling. “Victoria helped me out, what to write. I wanted to do it so perfectly that my hand almost cramped when I was doing it.”
By reaching the semifinals for her fourth straight tournament, Wozniacki guaranteed she will retain the No. 1 ranking through the upcoming two-week Sony Ericsson Open in Miami.
Sharapova needed more than two hours to overcome Peng in a match that featured 13 service breaks. They traded breaks in the first four games of the third set. Serving at 3-2, Sharapova won the final four games of the match, clinching it with an inside-out forehand off Peng’s second serve.
Robredo hurt himself in his straight-sets win over Sam Querrey, and an MRI on Wednesday night confirmed the injury, which will keep him out of the Miami tournament.
Del Potro has beaten three seeded players, including defending champion Ivan Ljubicic, to get this far. He’s in the semis for his fourth straight tournament after injuries derailed him for much of last year.
He has two days to practice and rest for Saturday’s semifinal against either top-ranked Rafael Nadal or Ivo Karlovic, who were to meet under the lights Thursday night.
“I believe much in my serve, in my game, and my weapons. So maybe against Rafa I can feel the same,” said Del Potro, who once ranked fourth in the world. “Even if I win, I know it’s a long road to be in the top again.”