Players have been struggling with the heat during this week’s tournament, with temperatures regularly exceeding 30C.
Francisco Comesana and Reilly Opelka both took medical timeouts during their third-round match, which was also interrupted for 45 minutes by rain.
Argentine Comesana won 6-7 (4-7) 6-4 7-5, saving three match points, but he needed medical attention in the second set, with a ball girl rushing to hand the 24-year-old a sick bag as he made his way gingerly back to his seat.
American Opelka, 27, also called for the doctor in the final set, complaining of dizziness and high blood pressure after being broken for 5-6.
Meanwhile, second seed Coco Gauff advanced to the last 16 without hitting a ball after Dayana Yastremska withdrew from their third-round tie because of illness.
The American, who won the tournament in 2023, will face Italy’s Lucia Bronzetti for a place in the quarter-finals.
Heavy rain and lightning led to the night session being suspended at 21:03 local time.
Men’s third seed Alexander Zverev was leading 6-4 5-4 and preparing to serve for the match against American Brandon Nakashima when they had to leave the court.
Jessica Pegula, seeded fourth, and Magda Linette were also unable to complete their match.
Linette won the first set 7-6 (7-5) but Pegula had just struck back to take the second 6-3 before the interruption.
Ben Shelton’s match with Roberto Bautista Agut and Clara Tauson’s meeting with Veronika Kudermetova were both moved to Wednesday.
