Jupiter - Dustin Johnson, a runner-up at this year's British Open, underwent right knee surgery on Tuesday which could keep the US star from taking part in January's season-opening US PGA Tour event.
Johnson had arthroscopic surgery to repair cartilage and is expected to be on crutches for up to a week before he begins chipping and putting. He expects to be able to resume practice in late December and play again in January.
It's uncertain whether or not Johnson will be ready in time to play in the Tournament of Champions, the opening event on the US tour. It begins on January 6 at Kapalua, Hawaii.
Johnson qualified for the opener by winning his fifth career US tour title at the Barclays last August, becoming the first player since Tiger Woods in 1999 to win an event in each of his first four PGA seasons.
Knee pain has nagged Johnson since July, when he finished in a share of second behind Northern Ireland's Darren Clarke at the British Open.
Johnson helped the United States retain the Presidents Cup with a victory over the Internationals two weeks ago at Melbourne.