On social media, Alcaraz writes that the injury occurred during an unnatural movement during training.

“I've worked so hard to be at my best for Australia, but unfortunately I won't be able to play.

It feels tough, but I have to be optimistic, make sure to recover and look forward," he writes.

The Australian Open begins in Melbourne on January 16.

Alcaraz won his first Grand Slam when he took home the US Open last fall, making him the youngest ever world number one since the ranking system was introduced 50 years ago.

Alcaraz missed the ATP playoffs and the Davis Cup due to an abdominal muscle injury he sustained at the Paris Masters in early November. 

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Holger Rune beat Carlos Alcaraz after he gave up due to injury.

Photo: TT