Alexander Zverev was hit with a point penalty for an audible obscenity during the fourth set of his US Open defeat (AFP Photo/TIMOTHY A. CLARY)

New York (AFP) - Alexander Zverev suggested his youthful rivals ditch the on-court antics and let their "racquet talk for them" -- somewhat ironically after the German incurred a point penalty for swearing in Monday's US Open loss.

The German singled out Daniil Medvedev, who has revelled in his role as tournament villain in New York, and Stefanos Tsitsipas as he advised the younger generation to follow the standards set by Roger Federer and Rafael Nadal.

"There's a lot of young guys that do things on the tennis court that maybe is not the best thing to do. I don't want the next generation to be known for that," Zverev said after his four-set defeat by Diego Schwartzman in the last 16 at Flushing Meadows.

Russian fifth seed Medvedev has twice thanked a hostile Louis Armstrong Stadium crowd for spurring him to victory, saying their boos had energized him after his second and third-round matches.

Medvedev was also fined $9,000 for an obscene gesture and unsportsmanlike conduct after stadium cameras spotted him lifting his middle finger to the side of his head away from the view of the chair umpire.

"Medvedev is obviously going over the line a little bit now. But he's winning. He's in the quarter-finals," Zverev said.

"At the end of the day it all doesn't matter if you're winning.

"But, yeah, I hope some of the NextGen or the young guys will kind of learn from the older guys like Roger and Rafa who have been unbelievable over their career, really let their racquet talk for them, not try to distract opponents."

Zverev also took aim at rising Greek star Tsitsipas, who tore into match umpire Damien Dumusois and several of his colleagues following a first-round US Open exit.

- Shoelace trouble -

He brought up Tsitsipas' recurring shoelace mishaps -- an at times comical, but irritating distraction that repeatedly surfaced during his semi-final run at the Washington ATP event last month.

"I think a lot of the times Tsitsipas gets over the line with changing his shoes 15 times in a tournament, going to the bathroom in the middle of a set. Stuff like that," Zverev said.

"Let your tennis racquet talk for you kind of. You don't need to do things to distract the opponent, try to win that way."

Zverev, long touted as a future Grand Slam champion, has struggled to replicate his best form at the majors and split with coach Ivan Lendl in July.

Former eight-time Grand Slam winner Lendl had told Zverev to "focus more on tennis" after he crashed out in the first round at Wimbledon.

He had embarked on his best US Open run before falling to Schwartzman and vowed to made a greater impact at the biggest events in 2020.

"This week there have been a lot of positives. I want to build on that. I want to get better," Zverev said.

"The Grand Slam calendar is done for me. It has not been the best, it has not been the worst. Generally my season so far has not been the best.

"Actually, Grand Slams were not worse than my season like they were last year and two years ago. I hope I can attack them next year."