Unsure of the relevant rule, Nick Kyrgios lost a point by running around the net to hit a ball that was going to land way out. He yelled at his guest box. He argued with the chair umpire. Most importantly, and has happened more recently for him than ever, Kyrgios won, eliminating defending U.S. Open champion and No. 1-ranked Daniil Medvevev.

Building on the momentum he built by reaching the Wimbledon final, Kyrgios moved into the quarterfinals at Flushing Meadows for the first time by beating Medvedev 7-6 (11), 3-6, 6-3, 6-2 on Sunday night.

The 23rd-seeded Kyrgios, a 27-year-old from Australia, never had managed to make it past the third round of the U.S. Open until now, going 0-4 at that stage until this year. But Kyrgios also never has managed to parlay his unquestioned skill into terrific play or any semblance of consistency the way is doing lately.

“I’m just glad I’m finally able to show New York my talent,” he said. “I haven’t had too many great trips here.”

He reached his first Grand Slam semifinal, then first Grand Slam final, at the All England Club in July, before losing to Novak Djokovic in the title match. Then Kyrgios won his first ATP title in three years at Washington in August. He followed that up with a victory over Medvedev at a hard-court tournament in Montreal soon after. He leads the ATP Tour in match wins since June.

And now, with his big serve producing 21 aces Sunday, and his go-for-broke style working perfectly against Medvedev, Kyrgios must be considered a serious championship contender at the U.S. Open.

Medvedev, meanwhile, was playing well enough to win all nine sets he played in Week 1 and look ready to give himself a shot at becoming the first man to win consecutive trophies in New York since Roger Federer grabbed the last of his five in a row from 2004-08.

Instead, Medvedev — whose victory over Djokovic in the 2021 U.S. Open final ended his bid for the first calendar-year Grand Slam in men’s tennis since 1969 — will relinquish the No. 1 ranking. Three players have a chance to replace him there: Rafael Nadal, Carlos Alcaraz and Casper Ruud.

On Tuesday, Kyrgios will meet No. 27 seed Karen Khachanov for a spot in the semifinals.