World number one Jannik Sinner admits he has endured a frosty reception from fellow players at the US Open following his failed anti-doping tests controversy.

The Italian was playing his first match since he escaped a ban despite two failed tests earlier this year.

Sinner, who was cleared of fault or negligence by an independent tribunal, has defended himself stoutly amid criticism he was shown favouritism with the speed in which his case was resolved.

It initially looked like the drama had taken its toll as American Mackenzie McDonald won the first set and then had a break of serve in the second, but Sinner assumed control and earned a 2-6 6-2 6-1 6-2 first-round victory.

Sinner said he had been pleased by the crowd’s reaction, but locker room reception had been a bit cooler.

“I’m curious to see how the reaction of the fans has been, but it has been very positive,” he said.

“I was very glad how the support was, also playing against an American, it’s a little bit different.

“So I’m happy [with] how I handled those situations, it was not easy.

“So I think a lot of positive things from today, and so let’s keep seeing what’s coming in the next round.

“There are some reaction from other players. I cannot really control what they think.

“You know, that’s how everything went and how it was.

“I cannot control the players’ reaction, and if I have something to say to someone, I go there privately, because I’m this kind of person.

“Overall, it has been not bad. So I’m happy about that.”

Former champion Daniil Medvedev booked his place in the second round with a 6-3 3-6 6-3 6-3 win over Serbian Lajovic.

Stefanos Tsitsipas became the highest seed to be knocked out after losing to Australian Thanasi Kokkinakis in four sets.

Felix Auger-Aliassiame, seeded 19th, also lost.

Carlos Alcaraz began his campaign with a four-set win over Australian Li Tu, who returned to the sport after six years away.

The Spaniard did not have it all his way on Arthur Ashe, losing the second set in a 6-2 4-6 6-3 6-1 win.

He said: “The second set I made 18 unforced errors. So that was the huge difference for me.

“He started to play better. That’s obviously serving better, playing more aggressive, and not making a lot of mistakes.

“I’m really happy to get through and get a chance to be better [in] the next round. Obviously, I felt well on court. I think I hit the ball well. I moved well.”