Rafael Nadal said his mysterious foot injury will not prevent him chasing an 11th Grand Slam title at Wimbledon after he advanced to a semifinal showdown with Andy Murray.

Nadal eased into the last four with a 6-3, 6-3, 5-7, 6-4 victory over Mardy Fish Wednesday, but later revealed he had been given a painkilling injection in his foot to help him through the quarterfinal tie.

The Spanish world No 1 and top seed had needed lengthy medical treatment to his left foot during Monday's fourth-round battle with Juan Martin del Potro, but a subsequent MRI scan revealed no serious damage.

Yet Nadal said the foot was still causing him problems which were being treated with a local anaesthetic.

"My foot is not fine. But we are in the quarterfinals of Wimbledon. It's an emergency, so I had to play," Nadal said.

Nadal said his medical team would put the injured foot "to sleep" for the remainder of the tournament.

"It's the last tournament in one month, or in one month and a half, so I have to try my best. It's always for me a dream to play here in Wimbledon.

"I'm in the quarterfinals and I had to do it, and I'm going to do it for the semifinals, too. When you sleep the foot you don't feel anything.

"I'm not worried about my foot. I went to the hospital. I did the MRI. I did the ultrasound. We didn't see anything really important. If you have something really important you have to go out of the tournament.

"I don't have nothing really important. But I have pain on the foot. I cannot run in perfect condition without anaesthetic. But with the anaesthetic, I feel nothing, I don't feel the pain."

Nadal said he initially feared the injury may have been similar to the stress fracture he suffered in 2004 which sidelined him for just under four months.

"I felt something similar during the match with del Potro. For that reason I was really scared," Nadal said. "But after when I did all the tests and the test was positive for me, I am not scared."

Looking ahead, Nadal is relishing the prospect of locking horns with Murray on Friday, whom he has beaten in his two previous matches at Wimbledon.

Overall, Nadal leads the Scot 11-4 in matches between the two, the most recent victory coming in the semi-finals at Roland Garros earlier this month.

"The match will be very difficult for me. I think he's playing at very, very high level," Nadal said. "For me the last few months of Andy was very, very good. We will see what's going on in the semifinals."