'I'm not certain to play at all at Tulsa, said Montgomerie after shooting 76 in the first round at the Marriott Forest of Arden, and then withdrawing after three holes on Friday.
'We'll have to see, but I can't say I'm a definite starter next week.'
'I hit into trees with my second shot and couldn't hook the ball round because I didn't have the back to do it, he added of his condition.
'I have a physio guy I see down in London and we'll see how I go after I've seen him.'
Montgomerie is a former seven-time winner of the Volvo Order of Merit title on the European Tour, and without a doubt the best player on the tour never to have won a major.
Montgomerie has competed in the United States Open since 1992, when he finished third to Tom Kite at Pebble Beach. His best finish is second, when only Ernie Els beat him in 97.
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