NEW YORK — Four-time major champion Maria Sharapova pulled out of the U.S. Open on Wednesday because of a right shoulder injury.

“Maria Sharapova is one of the great warriors of the tennis world,” U.S. Tennis Association Executive Director and COO Gordon Smith said. “If she withdrew, there’s a serious issue.”

Sharapova, the 2006 champion at Flushing Meadows, has played only one match on tour since her second-round loss at Wimbledon in June.

She originally was seeded third at the U.S. Open. The USTA said 2012 Wimbledon runner-up Agnieszka Radwanksa would shift from No. 4 to No. 3, and all other seeded players below her would move up a spot, too. Anastasia Pavlyuchenkova will become the tournament’s new 32nd seed.

The draw for the year’s last Grand Slam tournament is Thursday.