Timothée Chalamet "performed unbelievably well" at the ping pong table.

The 30-year-old actor secretly trained for years to play the title role in Marty Supreme, and his skill level really impressed the movie's table tennis instructor Diego Schaff.

Diego told The Hollywood Reporter: "In recreational table tennis, you barely move.

"This was very athletically demanding. He memorised every point, every movement, every shot. Timing was critical -- some shots float, others travel fast -- and he understood that immediately. He performed unbelievably well...

"He was singularly dedicated to getting this to be the same quality as the rest of the movie."

But one element of his game that Diego and his wife, US Olympian Wei Wang, worked on with Timothée was helping him unlearn modern technique to accurately show how the game was played in the 1950s.

He said: "We really dove into it last summer. We had to bring the mechanics of the strokes to a world-class level from the 1950s, which is distinctly different from how the sport is played today.

"Timothée being a dancer, he understood immediately how he needed to move. But we had to make that work within the context of relatively fast play.

"Different styles have very different strokes, and he understood all of it. He wasn't interested in doing the minimum. Even when he got it right, he'd say, 'Let's do it again.' "

The Oscar-nominated star performed all his sporting sequences himself because it was too tricky to find a stunt double.

Diego said: "We considered finding a double, but it was hard to find someone who matched his physique and could play.

"From the beginning, I told Josh [Safdie, director] we needed the best possible players, because they can perform under pressure.

"So we knew there was a limit to how far we could go. But Timothée understood the sport well enough to know how difficult a shot would be -- and then how it should look if you actually made it."

Diego hopes Marty Supreme will help table tennis get more of a platform.

He said: "I really hope this gives the sport the breakthrough it's deserved.

"People don't realise how many levels there are. You think you're close to the top, and there are 30 levels in between. The better you get, the more you realise how little you know.

"It takes a specific person -- like Marty. Someone who says, 'No matter how hard this is, I'm going to do this.' Hopefully we'll get more of those."