“Not the best match from my side. And I actually think not the best from his also,” the Russian said after the US Open quarter-final. “But, he won. So yeah, he was better.”

Jannik Sinner was just about better in a battle that was billed as the final before the final. Even though the overall quality remained far from it, the top-ranked Italian produced just enough quality from his end to enter the semi-final with a surprisingly momentum-swinging 6-1, 1-6, 6-1, 6-4 victory.

Sinner and Medvedev delivered two well-fought five-set matches at this year’s Australian Open and Wimbledon. In New York under lights, neither played lights-out tennis. And neither stayed at a high level long enough, or at the same time, for the contest to feel like one between the only Grand Slam-winning men left in this upset-hit US Open. Those sudden — and strange — switches in momentum, especially in the beginning of each set, were bemusing.

“I don’t have an answer yet, and I probably won’t on why it exactly happened,” Medvedev said.

What’s indeed happened is that Sinner has made his third semi-final in Majors this season, and his first at the US Open. The 2024 Australian Open champion, also the semi-finalist of this year’s French Open and last year’s Wimbledon, is the first man born in the 1990s or 2000s to go as far as at least the semi-finals of all four Slams. That list has only three other active players: Novak Djokovic, Rafael Nadal and Marin Cilic.

In a year where Carlos Alcaraz, 21, became the youngest man to sweep Slams across the three surfaces, Sinner, 23, has shown he could be just as good an all-court, all-season player. And, as the lone major finalist standing in the draw who will take on Great Britain’s surprise semi-finalist Jack Draper, the world No.1 is now the runaway favourite to back up his Slam breakthrough at the start of the season with his second right at the end.

Which, given all the chatter around his positive dope tests in the week leading up to the US Open and even during the tournament, says a lot about the Italian’s ability to block it all out and go about business as usual on the court.

“I have my team and my people who are close to me. And I always stick with the people who know me and believe in me. It’s very important,” Sinner said after beating Medvedev. “Obviously, in the beginning it was a tough situation, but day by day it went better.”

After dropping his first set at Flushing Meadows, Sinner has looked better with every set and match. Where he was also clearly better compared to Medvedev in the quarter-final was in his braver approach and finer execution at the net.

Sinner is not as natural there as from the baseline but, with the Russian’s court position so far behind, he got smart with his tactics. Sinner rushed to the net 33 times, and won 28 of those points for a high win percentage of 85 (Medvedev’s was 67%). He threw in plenty of slices and some serve-and-volleys in it too, which didn’t always work but it kept Medvedev yearning for rhythm from the back of the court.

“We tried to work really hard on this aspect of the game. I know I can improve a lot, especially going to the net,” Sinner said. “I tried to serve-and-volley a couple of times, trying to mix something in.”

The match, as a whole, remained a mixed bag. Medvedev was “horrible”, as he self-assessed, in the first set. The 2021 champion was happy he could problem-solve on the night, which, for the second set, was to get a lot closer to the baseline in attacking Sinner’s second serves. It worked, as Sinner was the one blown away this time. The wind turned again dramatically at the start of the third set, and Medvedev suddenly went back to his first-set mode.

Medvedev was left to problem-solve again, and he did for the early part of the fourth set that was the closest of all. At 2-3, Medvedev had a couple of break point opportunities, and he would rue the missed swinging backhand volley off the second. It was Sinner instead who got the break in the following game, and, like in the Australian Open final, the win over Medvedev.

“Maybe today I was going for a little bit more risky shots; I was missing a bit more. And then at one moment, I kind of got lost in my misses,” Medvedev said. “Maybe it was the same for him also.”

No one was quite sure what to make of this quarter-final. Surely, though, this is now Sinner’s Slam to lose.