Phil Mickelson has vowed to work on the "glaring areas" in his game after missing out on his sixth major title in the US PGA Championship at the weekend by one shot.

The 44-year-old was part of a tense ending to the tournament at Valhalla, but a bogey at the 16th gave Rory McIlroy the incentive to go on and win his fourth major title.

"I've got some regrouping to do these next three or four months," the Associated Press quotes Mickelson as saying. "I have some glaring areas in my game that I have to work on."

The American has not won a title since the British Open last year.