The 25-year-old Italian confirmed his decision on Saturday, ending hopes of a return at the ATP Masters 1000 event, which runs from 7 to 18 October.
Sinner extends lengthy absence
Sinner has not played since defeating Alexander Zverev in the Wimbledon final in July.
The injury subsequently forced him to miss the North American hard-court swing, including the US Open, before he also withdrew from the China Open in Beijing.
Sinner had hoped to return in Shanghai but said his recovery had not progressed sufficiently.
“Unfortunately, I won’t be able to play at the Rolex Shanghai Masters this year as I had hoped,” Sinner wrote on Instagram.
He also apologised to fans in Shanghai and said he looked forward to returning next year.
Sinner was Shanghai champion in 2024
Sinner won the Shanghai Masters in 2024, defeating Novak Djokovic in the final.
His withdrawal means he will not defend the title, although he has enjoyed an exceptional 2026 season. The ATP-listed record shows Sinner at 44-3 for the year, with Masters 1000 titles in Indian Wells, Miami, Monte-Carlo, Madrid and Rome before his Wimbledon triumph.
Zverev handed chance to challenge for No. 1
Sinner's absence also has major implications at the top of the ATP rankings.
Alexander Zverev is the Italian's closest challenger and can move to world No. 1 if he wins both the China Open in Beijing and the Shanghai Masters.
The Shanghai field includes four-time champion Djokovic, Zverev, Carlos Alcaraz, Daniil Medvedev, Ben Shelton, Felix Auger-Aliassime and defending champion Valentin Vacherot.
No return date confirmed
Sinner has not announced a specific date for his return to competition.
For now, the priority remains recovering fully from the knee problem before returning to the ATP Tour.
His continued absence leaves the closing stages of the 2026 season with an added layer of uncertainty, particularly with the battle for the world No. 1 ranking still open.