NEW YORK — Maria Sharapova pulled out of the US Open on Wednesday because of a right shoulder injury.
The US Tennis Association announced the 2006 champion’s withdrawal.
Sharapova has played only one match on tour since her second-round loss at Wimbledon in June.
Sharapova originally was seeded third at the US 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.
The USTA said Anastasia Pavlyuchenkova would become the No. 32 seed.
The draw for the year’s last Grand Slam tournament is Thursday. Play begins Monday.
Sharapova’s surprising exit caps a tumultuous couple of weeks for the four-time major title winner and former No. 1 player.
The Russian was sidelined by a hip injury after Wimbledon. Then she hired Jimmy Connors as her coach, an arrangement that lasted all of one match, a loss.
Sharapova last skipped the US Open in 2008, when she was off the tour for about 10 months because of surgery on her right shoulder.
She won her first major title since that operation at last year’s French Open, completing a career Grand Slam.
Earlier Wednesday, former top-10 player Mardy Fish also withdrew from the US Open, citing personal reasons, the latest setback in his bid to make a comeback on tour after dealing with heart issues.
Fish’s Twitter feed carried this message Wednesday: ‘‘Friends, unfortunately my health won’t allow me to compete this year at the US Open. Thank you for all your support.’’
He has missed months of action at a time over the past two seasons. On Tuesday, Fish stopped playing in the third set of his match against Jarkko Nieminen at a hard-court tournament in Winston-Salem, N.C., because of heat stroke.
He has played only eight matches on the ATP World Tour in 2013, going 3-5.
A year ago, Fish reached the fourth round at the US Open but withdrew before he was to face Roger Federer at that stage, saying it was for ‘‘precautionary measures’’ on doctor’s orders.
Fish missed about 2½ months earlier last season because of an accelerated heartbeat.
The night after he lost a match at Key Biscayne, Fla., in March 2012, Fish’s heart started racing uncontrollably. That May, doctors induced extreme palpitations to try to pinpoint the problem.
He is a three-time Grand Slam quarterfinalist — once each at the US Open, Wimbledon and the Australian Open, most recently at Flushing Meadows in 2011.