Roger Federer [Images] produced an extraordinary squash-style trick shot to dig himself out of a hole in his French Open semi-final against David Nalbandian on Friday.

Nalbandian eventually quit with an abdominal injury trailing 3-6, 6-4, 5-2 but the Argentine had led by a set and 3-0 before Federer's improvised stroke of genius turned the match.

Chasing back to retrieve a lob at 3-3 in the second set the world number one executed a mind-boggling forehand pass into the corner of the court from the baseline with his back to the net.

"It's all paying off, the squash I played over the years with my father early on," joked Federer, who is now one win away from becoming only the third man to hold all four Grand Slam titles at once.

"I don't know how I did it. It came out automatically. But maybe through squash, who knows? I enjoy the sport. If it helps me out in the semi-finals of the French Open, that's not bad."

Federer, who faces either defending champion Rafael Nadal [Images] or Croatian Ivan Ljubicic in his first Roland Garros final on Sunday, admitted he had suffered a real scare against Nalbandian.

"I thought I was going to lose. I just couldn't get the ball into play. I was shocked so I knew that something had to happen.

"That it took a shot like that, that's quite interesting. I can't pull off those shots on a consistent basis.

"But it's good. They give you a little bit of tailwind. They give you something extra, they get you going. That's exactly what I needed at that point."

On court Nalbandian smiled and shook his head in disbelief at the shot and afterwards said: "Incredible, incredible. It's not a usual type of shot."

FRESH FEDERER

The Argentine prides himself on his physical conditioning and said he was bitterly disappointed to have to retire.

"It's never easy when you lose and when you get injured, it's worse. But I was feeling that I was playing good, good tactically. The match was going perfect," he said.

"I'm going to fight if I'm okay. If I'm not okay, I mean, fight against what? It's impossible."

The Argentine faces a battle to be fit for Wimbledon which starts in just over two weeks.

"It's impossible to know," said Nalbandian, who reached the 2002 final on his debut appearance at the grasscourt Grand Slam. "I have to see a doctor and then we will make a decision what to do."

In contrast, Federer said he was feeling fresh before the biggest final of his career, when he will attempt to achieve his long-cherished goal of winning the claycourt Grand Slam.

"I think that's key here at the French Open, that you come such a long way and you feel pretty good," he said. "One thing's for sure, I won't lose because I'm tired."

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