Carlos Alcaraz has pulled out of the Australian Open after suffering a leg muscle injury in training.
The 19-year-old world number one won the US Open last September and would have been among the favourites at Melbourne Park and one of the players capable of challenging nine-time champion Novak Djokovic.
However, Alcaraz announced he would not be fit enough in time to feature, with a problem with a hamstring leaving him sidelined for the tennis season's opening grand slam.
He wrote on Instagram: "When I was at my best in preseason, I picked up an injury through a chance, unnatural movement in training.
"This time it's the semimembranosus muscle in my right leg. I'd worked so hard to get to my best level for Australia but unfortunately I won't be able to play the Care A2+ Kooyong or the Australian Open.
"It's tough, but I have to be optimistic, recover and look forward. See you in 2024 @australianopen."
The Kooyong event is an exhibition tournament ahead of the major, and it is the Australian Open where his absence will be most sorely felt.
Alcaraz has emerged as the pick of the new generation of players, with his high-intensity game winning him a legion of supporters and bringing him a host of titles already.
He earned $7.6million and picked up five singles titles last season, including the first grand slam crown of his career in New York, ending the year with a 57-13 win-loss record and the ATP top ranking.
Alcaraz's compatriot Rafael Nadal is the defending champion in Melbourne, while Djokovic returns this year after being deported from Australia 12 months ago amid a vaccination saga.