The most spectacular part?
Still, Novak stayed focused and he earned another break in game 12 for a 7-5, building the momentum before the rest of the match and another close set.
Murray saved a match point in game eight with a nice volley but Roger converted the second one after a solid smash, breaking his rival for the seventh time and delivering his fifth straight US Open crown, the last one in his career so far.
Kyrgios departs after causing a stir in his second-round win.
He'd lost just three times in an incomparable 1424-match career from such a commanding position and wasn't about to suffer a fourth such defeat at the hands of Kyrgios. He doesn't have a coach and wondered aloud, during the latest in a long line of news conferences that sound more like therapy sessions, whether he should add one - or perhaps someone who could help with the mental aspect of the game. He sprinted forward to chase a drop shot from the Australian and just managed to reach the ball before hitting a forehand victor around the net.
"Other guys play the shot they're supposed to hit, and then if they get beat, they're like, 'Maybe I should have hit Nick's shot.' Nick goes the other way around", said Federer, the No. 2 seed. "But that's just how he plays".
"We're two very different characters".
For many, his visit to NY this year was his tennis career in a nutshell.
Anderson's run to last year's final was a surprise, as at No. 32 he was the lowest-ranked U.S. Open finalist in the history of the ATP rankings. But Millman showed in that match that he could compete with Federer. Good luck extending that lead, go get 21.
Serena, seeded 17th, routed Venus 6-1, 6-2 in matching the most-lopsided victory in the Williams sisters' series.
Yes, Roger does reach the ball and yes, Nick Kyrgios was just as shocked as the rest of us. After No. 4 seed Angelique Kerber bowed out in a tough three-setter against Dominika Cibulkova, Alexander Zverev, the fourth seed on the men's side, faced the same fate.
Suarez Navarro, seeded 30th, next faces 2006 champion Maria Sharapova, who defeated 2017 French Open victor Jelena Ostapenko 6-3, 6-2.
The 2017 runner-up was beaten by Dominic Thiem 7-5, 6-2, 7-6 (2) on Sunday in a fourth-round match.
Federer explained his plan to negate Kyrgios's volatility was to play it safe and rely on his most consistent tennis.
Djokovic saved all five break points he faced to book a meeting with Joao Sousa of Portugal, a 7-6 (7/5), 4-6, 7-6 (7/4), 7-6 (7/5) victor over France's Lucas Pouille.