2021 French Open: What to Watch on Friday

John Isner, the 31st seed, does not have a game that would traditionally favor clay. Isner, a 6-foot-10 American, has a booming serve that favors him on hardcourts and grass, but he has worked in recent years to improve his ground game. This helped him as he broke his second-round opponent, Filip Krajinovic, three times in the second set. Now, Isner’s ground game will be tested to its limit as he looks for an upset.

Stefanos Tsitsipas of Greece, the fifth seed, has had a strong clay-court season, winning the Monte Carlo Masters and the Lyon Open and reaching the final of the Barcelona Open. Tsitsipas, 22, swept through the first two rounds of the French Open without dropping a set, and is a favorite to reach the final from his half of the draw. On Friday, he will have to find a way to adjust to Isner’s strong serve. If he can settle in on return games and get some early breaks, he should be able to control the flow of the match.

Court 14 | 5 a.m.

Casper Ruud vs. Alejandro Davidovich Fokina

Casper Ruud, the 15th seed, has spent the last few years knocking down national records that were once held by his father, Christian. This time, he will look to be the first Norwegian player to reach the round of 16 at more than one Grand Slam event after doing so for the first time at the Australian Open this year. Ruud picked up his second ATP title, and his second on clay, in Geneva last week.

Alejandro Davidovich Fokina, ranked No. 46, struggled in a five-set match against Botic van de Zandschulp in the second round. The match lasted 3 hours 42 minutes, with far more errors than winners coming from both players as they attempted to grind out long points and exhaust each other. It will be a challenge for Fokina, 21, to recover in time.