Japan's Kei Nishikori is out for the rest of the season after tearing a tendon in his right wrist.
The world number nine joins 12-time Grand Slam champion Novak Djokovic and Stan Wawrinka in missing the US Open, which starts on 28 August.
Nishikori, 27, is also one of seven top-10 players to pull out of this week's Cincinnati Masters.
"Kei hit a serve during practice and heard a 'pop' in his wrist," said a statement from his manager.
"At this stage, we have elected not to do surgery and Kei is in a cast.