Injuries Advance Woznizcki and del Potro to Semis at Indian Wells

Juan del Potro advanced at the BNP Paribas Open at the Indian Wells Tennis Center when 25th-seeded Tommy Robredo withdrew before their Thursday quarterfinal due to a strained left abductor muscle a day earlier. 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 semifinals for his fourth straight tournament after injuries derailed him for much of last year.

He will now meet top-ranked Rafael Nadal in Saturday’s semifinals. Nadal who is in pursuit of his third Indian Wells title, defeated big-serving Ivo Karlovic, 5-7, 6-1, 7-6 (7), to reach the BNP Paribas Open semifinals for the sixth consecutive year. Nadal won on his third match point after Karlovic’s forehand sailed long. Karlovic had hardly been playing like his number 239 ranking. He beat three seeded players to reach the quarterfinals, and pushed Nadal before losing to him for the fourth time.

On the women’s side, top-ranked Caroline Wozniacki reached the semifinals when Victoria Azarenka retired with a hip injury while trailing 3-0 in the first set. 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.

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. 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.

By reaching the semifinals for her fourth straight tournament, Wozniacki guaranteed she will retain the number one WTA ranking through the upcoming two-week Sony Ericsson Open in Miami.