Djokovic's cancelled session came the day after he had suffered what he described as a "nasty" fall, when he effectively did the splits when being wrong-footed by a shot from another Italian player Flavio Cobolli on his second match point in his quarter-final.
The 38-year-old had said afterwards on Wednesday that he would take medical advice and hoped to be back for the eagerly awaited last-four clash with the world no.1 on Centre Court.
"Obviously, body is not the same today like it was before, so I guess the real impact or effect of what happened I will feel tomorrow," he had said at his post-match conference.
"So let's see. I'm hoping the next 24, 48 hours that the severity of what was happening on the court and what happened is not too bad, that I'll be able to play at my best and free of pain in two days."
Djokovic had been scheduled to practice on Wimbledon's Aorangi Park courts between 1pm and 3pm, but the All England Club confirmed the session was cancelled.
He had the option to reschedule and practice later on Thursday, but there were no reports that he'd done so on either the indoor or outdoor facilities.
Sinner has had his own problems with an elbow concern, and similarly cancelled a practice on the eve of his quarter-final match with Ben Shelton, because he had hurt his right elbow when falling during his match with Grigor Dimitrov.
The Italian, though, reported no ill effects as he went on to defeat the American in straight sets, and he was out on the practice courts as usual on Thursday.
Djokovic, of course, has a history with injuries that he's so often overcome in the past. He had to withdraw before the quarter-finals of the 2024 French Open because of a knee injury that required surgery and yet still went on to reach the Wimbledon final after surgery.
At this year's Australian Open, though, he had to withdraw against Alexander Zverev because of a torn hamstring muscle.
Only twice has Djokovic stopped playing during a Wimbledon match. In 2017, he withdrew during a quarter-final against Tomas Berdych with elbow trouble; and in 2007 during a semifinal match against Rafael Nadal because of a foot problem.
With agencies