Roger Federer, of Switzerland, poses with a fan after defeating Nick Kyrgios, of Australia, during the third round of the U.S. Open tennis tournament, Saturday, Sept. 1, 2018, in New York. (AP Photo/Jason DeCrow)
Roger Federer, of Switzerland, poses with a fan after defeating Nick Kyrgios, of Australia, during the third round of the U.S. Open tennis tournament, Saturday, Sept. 1, 2018, in New York. (AP Photo/Jason DeCrow) Credit: ap — Jason DeCrow

New York — The most pivotal part of Roger Federer’s U.S. Open victory over Nick Kyrgios, both men agreed, came all of 17 minutes in, when the 20-time major champion was serving at 3-all, love-40 and got out of the jam.

The most spectacular part? That came, anyone who saw it surely would agree, much later. It was the on-a-full-sprint, drop-shot-retrieving, flick-from-a-few-inches-off-the-ground, forehand-around-the-net-post, jaw-dropping winner that Federer conjured up a few games from the conclusion of the 6-4, 6-1, 7-5 tour de force in the third round on Saturday.

“Almost unreal,” said Kyrgios, who admired the bit of racket wizardry with eyes wide open and mouth agape.

“A special one, no doubt about it,” declared Federer, who put it up there among his greatest hits, which, considering who we’re talking about, is certainly saying something.

There’s no rule mandating that the ball travel over the net for a shot to count, but Federer pointed out that this was not the sort of thing he can try in practice, mainly because there isn’t as much room to run wide of the court as in a big arena like Arthur Ashe Stadium, so “you will be running into a fence.”

Much was made of Kyrgios’ previous match, in which chair umpire Mohamed Lahyani climbed out of his seat to have a chat with the 23-year-old player about whether he was giving his best effort while trailing by a set and a break. Kyrgios went on to win; Lahyani was chastised by the U.S. Tennis Association for breaching “protocol,” but allowed to continue officiating at the tournament.

This time, of course, Kyrgios received no sort of counsel during the match other than all the muttering, at various volumes, he directed at himself. 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.

Two seeded men lost in the afternoon: No. 4 Alexander Zverev and No. 17 Lucas Pouille. Zverev still has never made the fourth round in visits to New York after being beaten 6-7 (1), 6-4, 6-1, 6-3 by Philipp Kohlschreiber in an all-German matchup, while Joao Sousa defeated Pouille 7-6 (5), 4-6, 7-6 (4), 7-6 (5). Kohlschreiber now meets 2014 runner-up Kei Nishikori, who got past No. 13 Diego Schwartzman 6-4, 6-4, 5-7, 6-1.

The No. 2-seeded Federer moved into the fourth round at Flushing Meadows for the 17th consecutive appearance. He’s won five titles at the U.S Open, although the last arrived a decade ago.

Next is what shapes up as a mismatch, facing 55th-ranked John Millman, who never before has made it this far at any Grand Slam tournament.

Win that, and Federer could find himself in a quarterfinal against 13-time major title winner Novak Djokovic, who faced Richard Gasquet in the third round later Saturday. That began after Maria Sharapova eliminated No. 10 Jelena Ostapenko 6-3, 6-2 to improve to 23-0 in night matches at the U.S. Open.

In earlier women’s action, there was a series of surprises, highlighted by Wimbledon champion Angelique Kerber’s 3-6, 6-3, 6-3 loss to No. 29 Dominika Cibulkova. Kerber, who counts the 2016 U.S. Open among her three Grand Slam trophies, was seeded No. 4, and joins No. 1 Simona Halep and No. 2 Caroline Wozniacki in making Week 1 exits — all in matches played on the new Louis Armstrong Stadium.

No. 6 Caroline Garcia and No. 13 Kiki Bertens also lost, while 2017 runner-up Madison Keys came back to beat Aleksandra Krunic 4-6, 6-1, 6-2.