Former World No. 1, Switzerland's Roger Federer came through a nerve-wracking third-round match against 27-year-old German Dominik Koepfer 7-6(5), 6-7(3), 7-6(4), 7-5 to seal a spot in the French Open pre-quarterfinals. In the late-evening match on Saturday, which went past midnight, saw the eighth seed and winner of 20 singles Grand Slam titles, stage a remarkable recovery from 2-4 down in the third set to finally winning the contest in three hours and 39 minutes. Federer advanced to the Round of 16 at a Grand Slam for the 68th time to extend his all-time record for most Round-of-16 appearances at the Grand Slams. World No. 1 Novak Djokovic is second with 54 Round-of-16 appearances, while 13-time French Open champion, Spain's Rafael Nadal is third with 50 appearances. Federer will next face ninth seed Matteo Berrettini in the pre-quarterfinals after the Italian got the better of South Korea's Soonwoo Kwon 7-6(6), 6-3, 6-4 to advance to the last-16 in Paris for the first time. This is the third time in the past week that the 39-year-old Federer has been tested, with his games against Uzbekistan's Denis Istomin and Croatia's Marin Cilic also extremely challenging. "I wasn't sure after the second set how much was left in the tank, so it was a good battle until then," Federer said. "I thought (this win)] was very important for me. I clearly hadn't practiced three hours (and) 35 (minutes), because that's obviously always pushing it. I pushed as much as I could, as we thought reasonable. But this today was I think a huge step forward for the team, and for all of us," Federer told atptour.com after the match.