Keegan Bradley withdrew from the BMW Championship before starting his third round today due to a possible rules violation on the opening day.

Bradley's third shot to the 18th hole in Thursday's first round came up short of the green, embedding in the steep grass face just above a bunker.

The former US PGA champion took relief (under Rule 25-2) for a ball embedded in its own pitch mark, chipped onto the green and two-putted for a double-bogey six.

However, after the round a spectator told Bradley he had seen the ball bounce before coming to rest, leaving the Ryder Cup wild card uncertain that he had handled the situation correctly.

Bradley consulted PGA Tour rules official Slugger White on Friday and was cleared of any potential violation after the two discussed the situation and examined the pitch mark, but Bradley remained unsure that he had dropped the ball in the right place.

In a statement from his management company, Bradley said: "I just feel withdrawing is the right thing to do to protect the field in the BMW Championship and the Tour Championship next week.

"It's eating me alive. I didn't call my fellow competitors for help in the first place and that bothers me. I know the official approved the drop but I just can't be absolutely sure it was the right spot."

Bradley began the week 28th in the FedEx Cup standings and is in danger of falling out of the top 30 who qualify for next week's Tour Championship. He had been in joint 41st in Denver after rounds of 71 and 70.