Alexander Zverev played down his poor record at grand slams after losing early again at the US Open.

The fourth seed was beaten 6-7 (1/7) 6-4 6-1 6-3 by German compatriot Philipp Kohlschreiber to fall in the third round of a slam for the third time this year.

Zverev is regarded as the leader of the next generation and has already won nine ATP Tour titles, three of them at Masters level, but success in best-of-five-set matches has proved a lot harder to come by.

The 21-year-old seemed to have taken a leap forward by battling into the quarter-finals of the French Open, winning three successive five-set matches, but he is yet to beat a player ranked in the top 25 at a slam.

Zverev said: “At tour events I lose as well. There’s just more tour events. You probably recognise it less. I lost to Robin Haase last week in Cincinnati. I lost to (Stefanos) Tsitsipas in Toronto. Those are not that great losses for me either.

“There’s a lot of focus on the grand slams. I’ve obviously done well in Paris, but not at the other grand slams this year maybe for different reasons.

“In Australia, I played against Chung (Hyeon), who played very well. Wimbledon I was still recovering from an injury. Here I played a good opponent. I just couldn’t find my best game today. Credit to him, he played very smart.”

Zverev added Ivan Lendl to his coaching team ahead of the tournament and is hoping the 58-year-old can follow his success with Andy Murray by turning him into a grand slam champion.

The German said: “It’s a process of developing. I took him to do well at slams. But this is a process. You can’t expect to immediately see the results. I think the results will come hopefully next year.”