Novak Djokovic has sweated his way to a round of 16 victory over Joao Sousa as the heat returned to the US Open, setting up a potentially mouth-watering quarter-final meeting with Roger Federer.
Djokovic did his part improving his perfect New York record in fourth round contests to 11-0 leaving it to Federer, who will take on Australian John Millman in the late contest on Arthur Ashe Stadium court to give the fans what would be a hotly anticipated match-up.
A Federer v Djokovic clash would provide the perfect contest to propel the US Open into the second week, with the two champions having claimed seven titles at Flushing Meadows between them.
Unseeded Sousa, the first Portuguese player to reach the fourth round of any grand slam, never looked a threat to progress any further as his run came to an end in two hours.
The biggest concern for Djokovic might well have been the conditions as the heat returned after a few days of relief.
The 31-year-old Serbian sixth seed left the court at two sets and 2-1 up for a medical evaluation.
The 13-times Grand Slam winner had made easy work of the opening set, breaking Sousa twice, the second time to close out set.
Things got tougher in the second as a sluggish Djokovic laboured before again clinching the set with a break.
As the temperatures rose so did the tempers, both players engaging in animated arguments with chair umpire James Keothavong over points.
Djokovic, however, was able to keep is cool just long enough to finish off Sousa with another late break.
Earlier on Monday, Kei Nishikori outclassed Philipp Kohlschreiber 6-3 6-2 7-5 to reach the quarter-finals.
The Japanese 21st seed, a finalist at Flushing Meadows in 2014 and a semi-finalist in 2016, fired 29 winners to end the run of veteran Kohlschreiber, who had beaten fourth seed Alexander Zverev in the previous round.
“(I was) really lucky to finish in three sets, it was really hot on the court,” Nishikori said in an on-court interview.
“I think we both struggled a little bit with the heat.”
Nishikori face seventh-seeded Marin Cilic, which will be a rematch of the 2014 final, or Belgian 10th seed David Goffin.