LONDON, ENGLAND - JUNE 29: Novak Djokovic of Serbia plays in his match with Frances Tiafoe of USA at The Hurlingham Club on June 29, 2023 in London, England. (Photo by Julian Finney/Getty Images)

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Novak Djokovic has made an annual habit of playing in the pre-Wimbledon exhibition known as the Giorgio Armani Tennis Classic in London.

But the 24-time Grand Slam champion withdrew without explanation ahead of Wednesday’s event.

Djokovic was set to face Russian Karen Khachanov who instead lost to American Martin Damm.

World No.1. Jannik Sinner beat Britain’s Cam Norrie in the first match.

Djokovic, 39, is the No. 7 seed at Wimbledon, with the draw set for Friday.

He has not played since losing to Joao Fonseca in the third round of Roland Garros.

Sinner enters Wimbledon as a massive favorite to defend his title (-225) with Djokovic (+400) and Roland Garros champ Alexander Zverev third (+800).

“There’s no doubt who the favorite is, it’s Sinner,” Patrick McEnroe said on a recent ESPN call with reporters. "He's the clear favorite. I would put probably Djokovic at the moment as the second favorite. I thought he played pretty well in Paris, even though he lost early. I thought he played three quality matches. That's going to give him confidence.

"Zverev I would not put as a favorite. I would put [Taylor] Fritz ahead of him. Fritz just beat him in a close match. I would probably put [Ben] Shelton slightly ahead of him.

"Other than that, as favorites go, it’s hard to find. "