Novak Djokovic says he will never forget being defaulted at the US Open but admits he cannot promise he will not misbehave on court again.

The world number one was disqualified from his last-16 match against Pablo Carreno Busta after striking a linesperson with the ball.

The Serbian, who said he was "extremely sorry" for his actions, was left feeling "sad and empty" over the incident, which saw him take a ball from his pocket and hit it behind him after dropping serve.

The 33-year-old is back in action this week at the Internazionali d'Italia in Rome, where he will start against either Tennys Sandgren or Salvatore Caruso after being given a bye in the first round.

Speaking to reporters on Monday, Djokovic said: "Of course, it was a shock to finish the US Open the way it was finished. It was the first time in my career that something like this happens.

"Of course, it could have happened earlier in my career, you know, could have happened to many players.

"The ball hits a line judge, it was just unfortunate that I hit the line umpire in a very awkward place. There was a lot of speculation and discussions whether it was deserved or not, I accepted it and I moved on.

"I cannot promise or cannot guarantee that I will never ever do anything similar to that in my life. I'm going to try my best, obviously, but anything is possible in life.

"I accepted it, I had to move on and that's what I did. Of course, I did not forget about it, I don't think I will ever forget about it, these things stay in your memory for the rest of your life, but I don't think I will have any major issues coming back to the tour and being able to perform well and hit the tennis ball during the point.

"I checked on [the line judge] after the match, she said that she was fine, that there were no injuries. I felt really sorry to cause the shock and drama to her, she didn't deserve that in any way, she's obviously volunteering as well, she loves tennis and has been there for quite a few years.

"It's unfortunate for both of us to experience that. It was very awkward and disappointing for me to finish off the US Open that way because I felt very good about myself, my game, I had won the Western and Southern Open.

"I came into the fourth round feeling really good and hitting the ball really nicely, and ready in every aspect. It was very unexpected and very unintended as well, to hit her.

"But when you hit the ball like that as I hit it to have a chance to hit someone who is on the court and the rules are clear when it comes to that."

Djokovic, who was unbeaten in 2020 prior to the US Open, has won the Internazionali d'Italia on four occasions, the last of which came in 2015.