Djokovic was due to practise for his match with Kudla at 5pm local time but it was pushed back to 6pm then 7pm.
The world No 1 finally showed up at around 7.25pm and worked on his game with his coaching team amid fears he may withdraw from the match.
But during the session, Djokovic stopped to confront a fan and via footage posted on Twitter can be heard telling the fan ‘trust me, I’ll come find you’.
Djokovic eventually resumed his session and worked on hitting backhands and serves to fully test his shoulder, which has been an injury issue for the past 10 days.
He left the court 8.30pm then at around 9pm, Djokovic stepped out for an interview with ESPN’s Tom Rinaldi before walking onto Arthur Ashe Stadium.
Rinaldi asked Djokovic about his injury but he was tight-lipped.
He said: “Let’s talk about that after.
“I’m here, I’ve given myself a chance. I believe it’s going to be fine. Let’s play.”
Speaking earlier in the day, former world No 1 Jim Courier said Djokovic’s problems were significant for the tournament.
“It’s affecting his serve, not just his backhand,” he said on the Tennis Channel.
“That’s the arm he uses to toss so perhaps the rhythm is off. He only served 51 per cent in play. He’s usually a mid-60s percentile serve.
“That’s a big deal so if he’s not able to solve this. He said in his post-match presser that he’s hoping with treatment and the right medical advice that he’ll be able to limit the pain, if not eliminate it.
“But he definitely was in a lot of discomfort in the match and that should be providing a lot of comfort for players in his section of the draw.”