The Spanish second seed kept his exposure to a minimum in 32 degrees Celsius conditions, taking an efficient 95 minutes to dispatch Serb Hamad Medjedovic 6-4, 6-4, for his 50th match win of the year.
“Medjedovic doesn’t like to run that much, so I tried to move him around as much as possible,” he said. “But it was difficult with the ball flying so much and his shots coming so fast. I tried to defend in a good way.”
Alcaraz has been on a tear in 2025 as he chases Jannik Sinner in the ATP rankings, and now owns 13 straight victories at the Masters 1000 level.
He will play for the quarter-finals against Luca Nardi after the Italian defeated Jakob Mensik 6-2, 2-1 with the Czech retiring after 42 minutes.
Five-time Grand Slam winner Alcaraz, who is preparing for the approaching US Open start, added: “I was really happy to get the win in a very difficult match.
“The season is very long and in at least half of your matches you don’t feel that good [physically],” he said. “But you have to stay positive and play your best tennis on the day. I’m proud about that. It’s a goal of the season.”
Francisco Comesano and Reilly Opelka both felt the heat of their mid-day match, which was interrupted for 45 minutes by rain, as the Argentine limped to a 6-7 (4/7), 6-4, 7-5 win while saving three match points.
Comesano needed a medical time out midway through the second set, but came back out to continue what turned into a fight of nearly three hours against the American.
Opelka called for the doctor just moments from his eventual loss, complaining of dizziness and high blood pressure after being broken for 5-6 in the final set.
After a quick consultation at his chair, Opelka was back on court to weakly scoop a return into the net on his opponent’s second match point.
The 71st-ranked South American will face ninth seed Andrey Rublev, who beat Australian Alexei Popyrin 6-7 (5/7), 7-6 (7/5), 7-5.
Opelka, noted for his big serve, fired 27 aces but also committed nearly 60 unforced errors. Comesano broke on four of his 13 chances.
He is the first Argentine into the Cincy round of 16 since Diego Schwartzman in 2022.
In the WTA draw, second seed Coco Gauff eased into the fourth round when opponent Dayana Yastremska withdrew due to an illness before their Tuesday match.
The American, who won the 2023 Cincinnati title and followed up with a US Open crown, will await an opponent from former Roland Garros champion Jelena Ostapenko and Italian Lucia Bronzetti.
Seventh seed Jasmine Paolini, last season’s Roland Garros and Wimbledon finalist, defeated American Ashlyn Krueger 7-6, (7/2), 6-1 while German qualifier Ella Seidel continued her strong showing with a 6-4, 2-6, 7-6 (8/6) defeat of McCartney Kessler.
Two-time Grand Slam champion Barbora Krejcikova outlasted American Iva Jovic 6-4, 3-6, 6-2. (AFP)