PIX: What's special about Djokovic's phone celebration

A dialed-in Novak Djokovic disconnected Ben Shelton's dream US Open run in the semi-finals on Friday, twisting the knife as he copied the young American's favoured on-court celebration after clinching it in three sets.

The veteran Djokovic held off a late-match surge from the 20-year-old to reach his 10th US Open final before he mimed answering the phone - and hanging up - to subvert the viral post-win gesture that Shelton has used in New York.

"I just love Ben's celebration," Djokovic told reporters with a grin.

"I thought it was very original, and I copied him. I stole his celebration."

Shelton said he had not seen Djokovic's move until after the match - but added that he would not tell another opponent how to celebrate.

"I think if you win the match, you deserve to do whatever you want," said Shelton.

"You know, as a kid growing up, I always learned that imitation is the sincerest form of flattery, so that's all I have to say about that."

The move is one that Shelton borrowed himself from three-times 110 metres hurdles world champion Grant Holloway, who seemed pleased to have his celebration brought to New York as he reposted photos and footage of Shelton on social media.

"It's kind of like I'm saying I'm dialed in," Shelton explained earlier in the tournament, when asked about the celebration.

The big-hitting Shelton earned legions of fans from the home crowd, even as he knocked out two higher-ranked Americans - Tommy Paul and Frances Tiafoe - in the fourth round and the quarter-finals, respectively.

"The two weeks as a whole was a good run for me. A lot of positives to take away for the rest of the year and going into next year," said Shelton.