SHANGHAI -- Pursuing a 100th career title, Novak Djokovic had an easier time in his second match at the Shanghai Masters in ousting Flavio Cobolli 6-1, 6-2 on Tuesday.
Djokovic clinched the match with his 19th winner, placing a forehand behind the Italian, who was racing back across the baseline after being pushed wide by the service.
The fourth-seeded Serb did not allow a break point in the third round, after previously being stretched to two tiebreakers and saving set points against Alex Michelsen of the United States.
"Cobolli was evidently exhausted after last night's match," Djokovic said of his opponent, who had advanced by beating three-time Grand Slam champion Stan Wawrinka. "I think that has taken a toll, physically, on him today."
Djokovic, who has won four of his 99 titles in Shanghai, next faces 61st-ranked Roman Safiullin, who upset Frances Tiafoe 5-7, 7-5, 7-6 (5).
Tiafoe congratulated Safiullin then walked off the court aiming expletives at the umpire, who had called a time violation minutes earlier on the 13th-seeded American's service. Tiafoe had tossed the ball in the air, though it was unclear whether it was an attempt to serve.
Later Tuesday, third-ranked Alexander Zverev also used expletives in an exchange with the umpire. A double bounce of the ball was correctly called when Zverev stretched to play a shot approaching the net.
Zverev converted his eighth match point to beat Tallon Griekspoor 7-6 (6), 2-6, 7-6 (5).
Stefanos Tsitsipas' rivalry with Daniil Medvedev will add another chapter after the Greek player beat Alexandre Muller 6-3, 7-5.
The 12th-ranked Tsitsipas and the Russian 2021 U.S. Open champion will meet for a 14th time, and their first in nearly a year. The fifth-ranked Medvedev has a commanding 9-4 lead in the head-to-head series, which has spilled over into a war of words off the court in the past.
"We've had some heated things on the court in the past, but I think those things have resolved themselves over time," Tsitsipas said.
Tsitsipas had to wait out a two-day rain delay to play his third-round match against Muller, but looked in complete control until losing his serve at 5-3 in the second set. Unperturbed, the Greek broke back to love to clinch the match and renew his six-year rivalry with Medvedev.
No. 16-ranked Ben Shelton put away Roberto Carballes Baena 6-3, 6-4, firing eight aces and 24 winners to line up top seed Jannik Sinner in the fourth round.
Seventh-ranked Taylor Fritz also advanced with ease, beating Japan's Yosuke Watanuki 6-3, 6-4, while Grigor Dimitrov, playing in his 100th Masters event, beat Alexei Popyrin 7-6 (5), 6-3.
Gael Monfils upset 15th-ranked Ugo Humbert 7-6 (7), 2-6, 6-1 in an all-French matchup. The 38-year-old Monfils, ranked 46th, is the second oldest player to reach the Shanghai fourth round in Shanghai, behind only Roger Federer (also 38) in 2019.
"It's never easy to play Ugo, he's really aggressive, playing fast off both wings and takes a lot of time from you," said Monfils, who plays second-ranked Carlos Alcaraz next.
Also, Tomas Machac, who made the semifinals in Tokyo, eased past Australian Aleksandar Vukic 6-4, 6-2 and next faces No. 13-ranked Tommy Paul in the third round.