South Africa's Kevin Anderson withdrew on Saturday from the U.S. Open due to a right knee injury, the U.S. Tennis Association announced.
Anderson was seeded 16th at this year's event, which begins Monday. He was the U.S. Open runner-up in 2017 when he lost to Rafael Nadal.
The 33-year-old is a two-time Grand Slam finalist. He also lost to Novak Djokovic at Wimbledon in 2018.
Anderson hasn't played in a tournament because of the knee since this year's Wimbledon in July.
Italy's Paolo Lorenzi replaced Anderson in the field. The lucky loser had failed to qualify earlier this week.
--Field Level Media