For much of his quarter final match at the US Open against Carlos Moya Friday night, Novak Djokovic looked miserable. At different points during one game, he bounced his racket on the ground, stared into space with his hands on hips and swiped the racket at his foot.

In the end, the third-seeded Djokovic pushed aside Moya 6-4, 7-6 (9-7), 6-1 to advance to the semi-finals against another Spaniard David Ferrer. In doing so, Djokovic advanced to the last-four stage of his third consecutive Grand Slam tournament.

And his mood brightened.

Asked by an on-court interviewer to show the crowd his impressions of other players, Djokovic proceeded to bring the house down with spot-on impressions of Maria Sharapova and Rafael Nadal preparing to serve.

For Sharapova, he pulled up his shorts to show more of his legs, hopped daintily and swept imaginary hair from his forehead. For Nadal, he pulled down his shorts to his knees, pushed up his sleeves, sprinted to the baseline and tugged at his underwear.

The crowd howled.

“Well, I enjoy it,” Djokovic said. “I’m really happy that the people accept it in a positive way. I’m not trying to make fun of Maria or Rafa or anybody else.

“Just trying to make the people laugh and have a good time, you know, trying to enjoy the tennis on the court and off the court as well.”

The night was perhaps the biggest coming-out party for Djokovic, the game’s emerging personality — a 20-year-old Serb who grew up in war-torn Yugoslavia and who seems to savour every moment of his success.

“I’m really happy that the people are looking at me in that way and are talking positive things about me,” Djokovic said.

“My goal is to be the No. 1 player in the world. I’ve been working for that all my life. And still I’m just 20, so I have a lot of time left. And of course priority is to play tennis, and the rest of the things are coming naturally.”

Now, with Nadal having fallen in the quarter final to Ferrer, Djokovic faces a different challenge in his first US Open semi-final.

Moya, 31 and a longtime Tour veteran, said he saw a bit of Djokovic’s imitations once he reached the locker room. “That’s a gift, and he does it very well,” Moya said. “So if he doesn’t succeed in tennis, maybe he has a good career in that.”

Djokovic said there was one player he has had trouble imitating.

“Well, the untouchable one, Roger,” Djokovic said, referring to Federer. “He’s too perfect for my style. Plus, I don’t have long hair.”

Djokovic laughed and paused. “I hope he doesn’t hear this,” he said.

Too late. Clearly, everyone is paying attention to Djokovic.