Roger Federer has vowed to be "fearless" when he takes on his old rival Rafael Nadal for the 39th time in the French Open semi-finals.
Having returned to the tournament after a four-year hiatus, Federer has produced some vintage form on the clay and he was superb in a 7-6 (7-4) 4-6 7-6 (7-5) 6-4 victory over fellow countryman Stan Wawrinka to make the last four for the first time in seven years.
Nadal leads his head to head against Federer 23-15 and has won all five of their matches at Roland Garros, most recently in four sets in the 2011 final.
It is 10 years since Federer last beat Nadal on clay, in the final of the Madrid Open, but he has won their last five matches.
"Against any player, there is always a chance," said Federer. "And that's exactly what everybody believes by facing Rafa. They know it's going to be tough. But you just never know.
"He might have a problem. He might be sick. You might be playing great or for some reason he's struggling. Maybe there's incredible wind, rain, ten rain delays. You just don't know. That's why you need to put yourself in that position."
The 37-year-old added: "For me to get to Rafa is not simple. It took five matches here for me to win to get there.
"I knew that when I signed up for the clay that hopefully that's going to happen. If I would have had a different mindset to avoid him, then I should not have played the clay. So I think by that mindset, I think it helped me to play so well so far this tournament.
"You have to be fearless to some extent to take on the spinney balls, the sliding balls, the kicking balls, and that's what I will do on Friday."
Nadal continued his march towards a record-extending 12th title with a straightforward 6-1 6-1 6-3 victory overKei Nishikori and is as excited as anyone to meet Federer next.
"For me, the main thing is being in the semi-final. The way that I have been playing has been very positive," Nadal said.
"Of course having Roger in front in the semi-finals is an extra thing. We shared the most important moments of our careers together on court facing each other.
"So it's another episode of this, and I'm happy for that and excited. It will be a special moment, and let's try to be ready for it."
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