Like a bottle of vintage wine, British Open champion Phil Mickelson believes he is getting better with age and says he has never been more motivated as a golfer.

The 43-year-old has recorded four top-threes in his past nine major starts and relishes the prospect of a head-to-head duel with Tiger Woods at this week's PGA Championship.

"I can taste some of my best golf coming out. I can feel it," Mickelson said after playing a practice round at Oak Hill Country Club on Tuesday.