On Wednesday night, the crowd at Arthur Ashe Stadium witnessed something they'd never seen before.
Novak Djokovic stood shaken and looking out of breath in the Flushing heat.
Just 90 minutes and only 14 games had been completed in the second round match against Laslo Djere.
Fans watched as the defending U.S. Open champion tried to cope with the heat during the changeovers, applying ice to his shoulders, changing his shirt and having a trainer massage his rib cage while looking disheveled.
However, the world number two did not retire midway through the match, as his fellow Serb retired due to injury, and he was awarded a walkover victory 6-4, 6-4, 2-0 in two hours and 16 minutes.
In the second set, Djokovic outscored him, but the Serb made just 47 percent of his first serves and double-faulted eight times, before Djokovic went up 4-3 in the seventh game and eventually won at deuce to tie the score.
“My serve hasn't been great in my first two matches here, so I'm just trying to find the rhythm and tempo of my serve,” Djokovic said after the match. “I knew going into the match that if my serve wasn't great, and it was, then I had to really work hard to extend the points, and I think that's why both sets were played over two hours.”
“In the end, it wasn't the outcome that we players and the spectators wanted to see,” Djokovic said. “I think it was because I was too physical in the first two sets. But of course, overall I'm happy with the win and happy that I got one more ball over the net than him in the key moments.”
The 29-year-old Jere threw his racquet to the ground and shouted in frustration at the box after losing the lead and suffering from what appeared to be an abdominal injury, which was treated by medical staff during a substitution.
Djokovic came from behind to win the second set, then after two games in the third set, Jere waved the white flag to win by default.
It was expected to be a tough match after Djokovic took the Serbian to five sets in the third round exactly one year ago. The Serbian underdog also beat Germany's Jan-Lennard Struff in a five-set first-round match on Monday.
Djokovic's next opponent in the third round of a Grand Slam is Australian Alexei Popyrin on Friday. Djokovic has beaten Popyrin at the Australian Open and Wimbledon this year, both times in four sets.
American Taylor Fritz defeated Italy's Matteo Berrettini 6-3, 7-6 (1), 6-1 to reach the third round of the U.S. Open.
The top-seeded American in the men's singles will face Francisco Comesana of Argentina on Friday.
