Karen Khachanov was 21 years old and ranked No. 48 in the world when the 2018 season began. The first signs that he was carving a new trajectory came early in Marseille, where he defeated Tomas Berdych and Lucas Pouille – both Top 20 players – on the way to his second career title. Stellar results followed – he made the fourth round at both Roland Garros and Wimbledon and was a semi-finalist in Toronto.

The big leap came in the fall, when he won the titles in Moscow and, almost inexplicably, the regular-season finale in Paris. His last three victories came against No. 5-ranked Alexander Zverev, No. 8 Dominic Thiem and, in the final, No. 2 Novak Djokovic. Khachanov, the first unseeded player to win an ATP Masters 1000 since David Nalbandian 11 years earlier, won 46 matches that season, was the first alternate at the year-end Nitto ATP Finals in London and finished the year ranked No. 11.

How on earth did that happen?

“To be honest with you,” Khachanov said Saturday from the Astana Open, “I don’t know. Sometimes, things happen that you cannot predict. I had a great run at the end of 2018. Because with one result you can make it into the Top 10.”

And while Khachanov rose to a career-high No. 8 early the following year, in the four seasons since that breakthrough – with the exception of a silver medal in singles at the Olympics played in Tokyo a year ago – he has never regained those giddy heights. But there are signs that when he plays American Maxime Cressy in a first-round match at the Kazakhstan National Tennis Centre you might see him starting to again approach that level.

In a year that has seen him win 31 matches, his finest moments came in the most recent event he played, the US Open. His eighth trip to New York, including qualifying, produced his best result: a berth in the semi-finals, a career-best major effort.

He defeated No. 15-ranked Pablo Carreno Busta in the fourth round (in five sets) and No. 25 Nick Kyrgios in the quarter-finals, in another match that went the distance. After five consecutive victories, the run finally ended against Casper Ruud.

“I was wishing, of course, to have a cherry on the pie and to lift the trophy,” Khachanov admitted. “The deeper you go, the more you believe that you can do it.”

Khachanov has always had a formidable serve and a forehand to go with it. At the US Open, he was using them in a devastating one-two combination. The confidence that carried him so well four years ago, seemed to return.

“Confidence, obviously, is a very interesting thing,” Khachanov said. “It’s what matters most. You can believe in yourself [going in] – that you can do it – but once you achieve the result, that’s the actual thing that you can feel.”

Khachanov should be feeling it in Kazakhstan; his ranking moved up 13 spots after the New York fortnight, to No. 18. He’s scheduled to play here, then Antwerp, Vienna and Paris. He’s currently 17th in the Pepperstone ATP Live Race To Turin, but a title at one of his remaining events could put him within striking distance. His history, he knows, suggests he’s capable of a late run.

“It’s still a long way,” he said. “And still a lot of points to be played. It’s been a great run and I use it was a motivation for the next achievements. I think this is a step forward.

“I think step by step I’m improving and raising my game. And I think I’m a better player today than I was [four years ago]. At the end of the day, the results, they don’t show that. But, hopefully, in the long run, it will show.”