Nick Kyrgios, on a roll, storms into his first U.S. Open quarterfinal

He made the quarterfinals at a prime U.S. Open tuneup event in Montreal, the tournament after that.

And on Sunday, on a humid night at Arthur Ashe Stadium, he knocked off world No. 1 Daniil Medvedev, 7-6 (13-11), 3-6, 6-3, 6-2, to reach the quarterfinals of the U.S. Open for the first time.

It was his second victory over the world No. 1 in a month, a result that will knock Medvedev down in the rankings. Anyone who doesn’t fear Kyrgios by now must not be watching.

“I’m just glad that I’m able to show New York my talent. … Finally,” Kyrgios said on court afterward. “It took me 27 years.”

The air was so heavy it might have had texture Sunday following a light afternoon rain, and a Kyrgios-Medvedev matchup had all the makings of an on-court storm. Their Aug. 10 battle in Montreal had gone the maximum three sets men play at tournaments that aren’t Grand Slams, and a raucous crowd settled in for the show.

They played like lightning. Medvedev rained down 22 aces to Kyrgios’s 21 while Kyrgios had 53 winners to Medvedev’s 49. Rarely did an extended rally end without one player provoking a reaction from spectators — or the umpire or the other player.

The most baffling such moment was in the third set, when Kyrgios lost a point by running around the net to hit a ball that was going to land way out. He celebrated afterward by holding up a finger and smiling with glee, apparently unaware of the rule that had just cost him a break point.

“I still can’t believe the boneheaded play I made over here. I thought that was legal!” he said.

The Aussie’s usual antics were present, from unloading on his box to chirping at the chair umpire for starting the serve clock too quickly. But nothing distracted Kyrgios from the task, and his all-out aggression worked flawlessly against Medvedev’s wily game.

“Yeah, it was a high-level match,” Medvedev said. “Played Novak [Djokovic], Rafa [Nadal]. They all play amazing. Nick today played kind of their level, in my opinion. He has a little bit different game because he’s not like a grinder in a way. At the same time, he can rally.”

They rallied endlessly in a first set that screamed on for 63 minutes, including a tiebreaker that refused to die. After staving off three Medvedev set points, Kyrgios earned two himself and flubbed both, turning and thundering at the entourage in his player box.

“Tell me what to do! Say something,” he yelled.

They responded with nothing but encouragement, which seemed to be all Kyrgios needed. Two set points later he sealed the set.

His level dipped momentarily as Medvedev tried to stage a comeback by taking the second set, but Kyrgios regrouped and raced out to a 4-1 lead in the third to quash any notion of that. Kyrgios took the final two sets in 74 minutes while Medvedev looked wearier with every point.

He advances to face big-hitting Russian Karen Khachanov in the quarterfinals Tuesday with a shot at his second consecutive Grand Slam semifinal at stake.

The difference between the Kyrgios of just a few months ago and the man who leads the ATP in tour victories since June is all mental. The Aussie said earlier this summer that losing the Wimbledon final to Djokovic motivated him to tear through the rest of the season.

Now when he thinks of the run, he sees all that he gained, not what he lost.

“I look back, it was just all a learning process to now because I’ve matured so much. I feel like I kind of embrace it all. When I’m playing bad, I embrace it; when I’m playing good, I embrace it. But I stay the same, where before I used to just ride the highs and lows way too much and I was exhausted. I didn’t know how to deal with everything else as well,” Kyrgios said.

“I know the process now of what it takes to get to a final of a Grand Slam. Not to win it yet but to get to the final. I know the process. You can’t avoid it.”