Roger Federer survived five sets and over three hours with Mikhail Youzhny of Russia Thursday to advance to the third round of the U.S. Open. After taking the first set 6-1, Federer dropped two straight, then won the final two to secure the victory.

Youzhny appeared to injure his left foot in set five, the The New York Times reports.

Federer improved to 17-0 head-to-head against Youzhny. He is a perfect 12-0 against his third-round opponent, No. 31 seed Feliciano Lopez.

Federer also went the distance to prevail over American Frances Tiaofoe in the first round Tuesday. He has never opened a slam with back-to-back five-set matches, according to the Times.

“These five set battles are actually quite a lot of fun and I feel quite warmed up by now,” he said with a touch of irony.

The 36-year-old has battled a back injury that forced him to withdraw from the Cincinnati Masters in mid-August. Though he said after Tuesday’s match that the injury did not bother him, Federer admitted, per the Times’ most recent report, to playing “cautiously” in the early stages of his win over Tiafoe.

Thursday, he said his back was feeling “much better.”

Federer has not demonstrated concern about the injuries, nor does he appear to be losing sleep over the fatigue that may begin to dog him as the tournament progresses.

“Yes, I might feel more tired than I normally would going into the third round, but that’s O.K.,” Federer said. “I think I just need to get more consistent because I’m not playing all that bad, I just am going up and down in waves through out the match.”

Rather than practicing for Thursday’s match at the designated practice facility, the Times reports, Federer hit the courts in Central Park.

“Anything that doesn’t make me drive very long,” he said. “I really liked the idea of playing in Central Park for the first time.”

Meanwhile, on the other side of the men’s draw, Rafael Nadal overcame a rocky first set to defeat Taro Daniel of Japan, 4-6, 6-3, 6-2, 6-2. He will face Leonard Mayer of Argentina in round three.

Seven-seed Gregor Dimitrov of Bulgaria, who won his first masters tournament in Cincinnati, fell in straight sets (5-7, 6-7 [3], 3-6) to Russian teenager Andrey Rublev. In a tournament from which world No. 2 Andy Murray, No. 4 Stan Wawrinka and No. 5 Novak Djokovic are all absent, Dimitrov was the highest-seeded player between Nadal and the quarterfinals.

Rublev is ranked No. 54 in the world. At 17, he is among the youngest players in the Top 100. This year’s Open marks his first trip beyond the second round of a Grand Slam. His first ATP Title came at the Croatia Open in late July.

No. 24 seed Juan Martin Del Potro of Argentina ousted qualifier Adrian Menendez-Maceiras in straight sets, 6-2, 6-3, 7-6 (3). In round three, Del Potro will face 11-seed Roberto Bautista Agut of Spain, who beat Dustin Brown of Germany, 6-1, 6-3, 7-6 (3) in round two.

On the women’s side, Karolina Pliskova overcame a first-set loss to beat American Nicole Gibbs.

“I think she was playing really aggressive from the baseline,” Pliskova said of Gibbs after the match. “I’m just happy I closed it with my serve.”

Gibbs won the opening set convincingly. Pliskova showed signs of frustration, but held on to win, 2-6, 6-3, 6-4.

Gibbs, 24, has yet to win a WTA (Women’s Tennis Association) title, though she has won four ITF (International Tennis Federation) championships.. She is ranked No. 127 in the world.

Pliskova will need to appear in the Open final in order to retain her No. 1 world ranking. Otherwise, five different women are in line to assume the top spot by the end of the tournament.

One such woman is Elina Svitolina, who beat Evgeniya Rodina of Russia by a score of 6-4, 6-4 at Ashe Thursday.

“I don’t think about those things [i.e., rankings],” Svitolina said on the broadcast after her match. “Of course, for each player, to reach No. 1 in the world is a massive deal and it’s great, but I really want to go far in this tournament and take it one match at a time.”

Americans Madison Keys and CoCo Vandeweghe both advanced Thursday.

American Jennifer Brady, who entered the tournament ranked No. 91 in the world, upset No. 23 seed Barbora Strycova of the Czech Republic 6-1, 6-1.

“I came out with lots of energy and I played her before, so I knew what to expect,” Brady said in an on-court interview. “I think I learned her game style and the way she competes. I knew it was going to be a tough match, so I brought my A game and I’m happy I played well.”

U.S. Open play continued Friday.