ARDMORE, Pa. — Louis Oosthuizen has withdrawn from the U.S. Open with a hip injury.

The 2010 British Open champion strained a hip flexor while shooting a 5-over 75 in the first round and pulled out before his second round tee time Friday.

Oosthuizen said the problem affected his swing to the point that he was advised he risked further damage if he kept playing.

The South African's best finish at the U.S. Open came in 2011, when he tied for ninth.