Reigning British Open champion Darren Clarke withdrew from the U.S. Open on Monday due to a lingering groin injury.
"I am extremely disappointed as Open champion that I am unable to play the U.S. Open," Clarke said in a statement on his management team's website. "But I have to make sure I am 100 percent ready for Royal Lytham and to do that I have been advised not to play for a month."
The U.S. Open is scheduled for June 14-17 at Olympic Club in San Francisco, Calif.
Clarke will also miss the Nordea Masters next week on the European Tour.
According to the statement, Clarke, who cruised to his first major title last year at Royal St. George's Golf Club, will return in time for the Irish Open on June 28 at his home course of Royal Portrush in Northern Ireland.
Also, according to the statement, Clarke noticed the injury first at the Houston Open the week before the Masters. He felt it again last week at the BMW PGA Championship.
Clarke hasn't made the weekend on either the PGA Tour or European Tour since the WGC-Cadillac Championship in early March, an event with no cut. In two match-play events, Clarke lost in the first round of the WGC-Accenture tournament, and didn't make the field of 16 at the Volvo World Match Play.
"I haven't been able to get through the ball properly because of it and I don't want to take any chances," said Clarke.