The 44-year-old American, who is a five-time Major winner, has only recorded one top-10 finish this season, but has stressed that he is not on the way down.
Furthermore, 'Lefty' has vowed to achieve some more career highlights before the end of the decade.
"The parts feel a lot better than the whole right now," he told reporters. "I believe the next five years are going to be some of the best of my career."
Mickelson, who has won three Masters titles and also lifted the USPGA Championship in 2005, secured a maiden Claret Jug when he triumphed at Muirfield 12 months ago.