World number one Jannik Sinner will not play again in 2026 because of an ongoing right knee injury.
The Italian has not played competitively since defending his Wimbledon title in July.
Five-time Grand Slam champion Sinner said he “needed to think about my long-term career” when deciding to end his season early.
“Me together with the doctors have decided that I need a course of treatment for my knee,” the 25-year-old said in an Instagram video.
“The last couple of years gave me so many beautiful feelings and emotions, which this year is going to be way different.
“I will do everything possible to get back 100%.”
Sinner was the dominant player for much of the year, winning 44 and losing just three of his singles matches.
He won five Masters 1000 titles in a row between March and May, becoming the youngest man to complete the ‘career Golden Masters’.
Sinner’s injury means that Alexander Zverev is highly likely to replace him as world number one by the end of the year.
Second-ranked Zverev, who has won the French Open and US Open this year, trails Sinner by 1,280 points in the live rankings.
However, Sinner will be unable to defend the points he claimed with title triumphs in China, Vienna, Paris and the ATP Finals at the end of last year.
Sinner won six titles in 2026 on all three surfaces and lost just one singles match between March and July.
He reached the semi-finals of the Australian Open, losing in five sets to Novak Djokovic, but suffered a shock second-round exit at the French Open in May.
The loss to Juan Manuel Cerundolo in hot and humid Paris conditions ended Sinner’s 30-match winning streak.
However, he bounced back superbly at Wimbledon. Despite being taken to five sets in the first round – and bleeding through his shoes at one point – he recovered to eventually beat Zverev in the showpiece and defend his title.
Sinner and generational rival Alcaraz, having met in three of the four Grand Slam finals last year, only played each other once in 2026.
Sinner came out on top, beating the Spaniard in the Monte Carlo Masters final to replace him as world number one.
He finishes the year with a 10-1 record against top-10 players, with his sole defeat coming against Djokovic in Melbourne at the start of the year.