Rory McIlroy has confirmed he will have an MRI scan on the injured right wrist which he suffered during his opening round at the USPGA Championship.
Northern Ireland's US Open champion hurt the tendon and also his right forearm when striking an iron against a tree root on the third hole.
McIlroy said: "I'm going to go and get an MRI scan now and see there's no damage done to it."
He explained at a press conference: "It was dangerous. I thought maybe the tree root was a foot in front of the ball and thought if I could make contact with the ball and let the club go I could get away with it. In hindsight I would have been better to chip out sideways and still get a five.
"But it was a shot where I thought if I took it on and pulled it off it could have saved me a shot. I've obviously gone through impact. I held on to the club too long and jarred my right wrist and right forearm. It was obviously very painful after that."
Steve Stricker claimed the first-round lead after a major record-equalling seven-under 63.
The American led by two from Jerry Kelly and by three from their fellow American Shaun Micheel, winner in 2003.
Ireland's Padraig Harrington battled round the course to card 73. Open champion Darren Clarke is four shots further back on seven-under alongside Tiger Woods and in danger of missing the cut.