OAKMONT, Pa. - Battling an injured left wrist, Phil Mickelson struggled but hung tough in the first round of the U.S. Open on Thursday.

Mickelson, whose final-hole collapse at Winged Foot last year cost him a fourth major and his first U.S. Open title, finished 4 over. Lefty injured his left wrist chipping out of Oakmont's thick-as-steel rough several weeks ago and was unable to play a full practice round this week.