Frenchman Gael Monfils upset fourth-seeded Stefano Tsitsipas in straight sets on Wednesday at the National Bank Open in Toronto in just his 11th match of the year.
Monfils, 36, defeated Tsitsipas 6-4, 6-3 in the ATP 1000 event in just one hour and 25 minutes. Monfils has been battling injuries this year.
"I knew that Stef had a lot of confidence," Monfils said afterward. "He would try to go for his shots. I tried to put a lot of balls in, tried to hit quite heavy and not let him dictate too much. I think I did it well."
The top two seeds in the tournament were able to avoid upsets, though both needed to put in a little extra work in the second set en route to sweeps.
Top-seeded and world No. 1 Carlos Alcaraz of Spain had little trouble in the first set with unseeded and fellow 20-year-old Ben Shelton of the United States, winning 6-3. But Shelton went point-for-point with the Wimbledon champ in the second set, holding serve every service game and taking Alcaraz to deuce once. But Alcaraz broke Shelton on consecutive service points in the tiebreaker and rolled to a 7-6 (3) win to take the match.
Second-seeded Daniil Medvedev cruised into the third round by beating qualifier Matteo Arnaldi of Italy 6-2, 7-5. The 22-year-old Arnaldi held serve throughout much of the second set before dropping serve while trailing 6-5 to lose the match.
American qualifier Marcos Giron knocked off fifth-seeded Holger Rune of Denmark in three sets, 6-2, 4-6, 6-3 in a match that lasted more than two hours.
Russian and No. 6 seed Andrey Rublev lost in straight sets to unseeded Mackenzie McDonald, 6-4, 6-3. McDonald hit 21 winners against just five unforced errors to oust Rublev.
The No. 7 seed, Jannik Sinner, had little trouble with fellow Italian Matteo Berrettini, winning 6-4, 6-3 in 90 minutes. After breaking Berrettini on the final game of the first set, the 21-year-old Sinner broke serve on his first chance in the second set and never looked back.
No. 8 Taylor Fritz needed two hours and 28 minutes to down Ugo Humbert of France 7-6 (7), 3-6, 6-3. Fritz survived nine double faults and 13 aces by Humbert. Fritz improved to 28-7 on hard courts in 2023.
In perhaps the most competitive match of the day, 12th-seeded Tommy Paul of the United States traded tiebreak wins in the first two sets before taking the third set to beat Francisco Cerundolo of Argentina, 7-6 (2), 6-7 (2), 6-3 in 2 hours, 48 minutes.
In other action, Spain's Alejandro Davidovich Fokina converted four break points to upset No. 13 Alexander Zverev of Germany 6-2, 6-1. No. 15 Hubert Hurkacz of Poland rallied to defeat Serbia's Miomir Kecmanovic 5-7, 6-3, 6-0. No. 16 seed Lorenzo Musetti of Italy also had to rally to get past Aussie qualifier Thanasi Kokkinakis 4-6, 7-5, 6-4. Wild card Milos Raonic of Canada also toppled qualifier Taro Daniel of Japan 6-4, 6-3 and Australia's Alex de Minaur recorded a 6-4, 7-5 victory over Canada's Gabriel Diallo.
—Field Level Media