Swiss tennis players Roger Federer and Stanislas Wawrinka, seeded two and 17 respectively, have both advanced to the third round of the French Open.
But Federer had to rally on Thursday against world number 45 Jose Acasuso of Argentina before eventually winning 7-6 (8), 5-7, 7-6 (2), 6-2.
The three-time finalist at Roland Garros struggled to get his shots in on centre court, but still managed to do enough to win despite trailing 5-1 in the third set.
"It was really tough," Federer said. "The first three sets could have gone either way."
Federer was in danger of ending his record of 19 consecutive grand slam semifinal appearances, but instead won five straight games to send the third set to a tiebreaker, which he won easily.
The last time Federer lost before the semifinals was the 2004 French Open, when he fell in the third round.
On Wednesday Wawrinka, who has never made it past the third round at Roland Garros, beat Nicolas Massu from Chile, 6-1, 6-1, 6-2 to set up a match with tenth seed Nikolay Davydenko.
Federer now faces 32nd seed Paul-Henri Mathieu.
swissinfo.ch with agencies
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