World number one Roger Federer reached the last four of the Pacific Life Open without hitting a shot on Friday when his quarter-final opponent Tommy Haas pulled out with a sinus infection.
Swiss Federer, three times champion at Indian Wells and seeking his first ATP title of the year, will next meet unseeded American Mardy Fish, who scraped past seventh-seeded David Nalbandian of Argentina 6-3, 6-7, 7-6.
"I deeply regret that I have to withdraw," German Haas said in a statement. "I was playing my best tennis of the season and was looking forward to playing Roger this afternoon.
"I am sure the tennis will be incredible this weekend and I look forward to returning again next year."
The 29-year-old, a former world number two whose career has been dogged by injuries, produced an impressive run this week, knocking out sixth-seeded American Andy Roddick and Britain's number 11 seed Andy Murray.
Top seed Federer, who has beaten Haas eight times in 10 career meetings, said: "I am very sorry for Tommy as I was looking forward to another great match with him.
"We have played quite a few times and I know and respect Tommy a lot. I hope he gets better quickly."
Fish, who upset fourth-seeded Russian Nikolay Davydenko in the third round, squandered two match points in the 10th game of a protracted third set against Nalbandian before sealing victory in two hours, 45 minutes.
The Argentine, who had lost to Fish in their only previous career meeting, broke the American in the 11th game to lead 6-5 but failed to serve out for victory in the 12th.
LATE CONTROL
Nalbandian double-faulted to be broken and Fish took late control of the tiebreak, a forehand winner putting him 6-4 up before he booked his place in the last four with an overhead smash.
"This feels great," Fish, 26, said in a courtside interview after falling to his knees and rocking back in celebration.
"David is a tremendous opponent and he's got a heck of a record in coming back in matches, and that was in the back of my mind. It was great to have the crowd on my side.
"You're never in a great situation when the guy is serving for the match," added the American, ranked 98th in the world. "I'd be lying to you if I just said I felt like I was going to break right there and win the match."
Nalbandian, who clinched his eighth ATP title in Buenos Aires earlier this year, paid tribute to Fish's play in the final set.
"The third set was very tight," the 26-year-old Cordoba native said. "We didn't break each other until the end. I think he played a very good game at that moment.
"When the surface is fast, he's very dangerous all the time, so it's not strange for me to see him play like that."
Saturday's other semi-final will be between holder Rafael Nadal of Spain, seeded second, and third-seeded Australian Open champion Novak Djokovic of Serbia.
