Phil Mickelson says diet and exercise are the keys to longevity. Photo: Orlando Ramirez-USA TODAY Sports

AUGUSTA – Five-time major winner Phil Mickelson claims age is no barrier as he bids to end a near four-year victory drought and become the oldest Masters champion in history.

Diet, exercise, fitness and specifically a 'no sugar' rule are his key to longevity on the golf course and Mickelson believes the combination could unlock a sixth major victory for the 46-year-old champion from California.

Jack Nicklaus, winner of a record 18 major titles, is the oldest Masters winner in history, winning the green jacket at age 46 in 1986.

But Mickelson, also 46, would be his senior by several months if he manages to collect his fourth Masters title on Sunday.

"I don't think much about age right now," said Mickelson, who has also won the British Open and the PGA Championship titles and finished second at the US Open a record six times.

"I think that guys' careers are being extended a lot longer because of the way fitness has taken over."

"And it's not like I'm a pillar of fitness, but I spend a decent enough time to be able to physically perform and practice and play the way I'd like to play."

Powerfully built but spare-framed, Mickelson says the golden rule for continuing to compete at the highest level is to avoid refined sugar whenever possible.

"For recovery and to get rid of inflammation, I've had to reduce or stop any type of sugar intake, like 95 percent of it," he said.

"It causes so much inflammation in my body and I'm not able to recover. Any type of processed sugar is just a catastrophe for me to eat. Still do though, at times," he joked.

Mickelson, who last tasted success when he won the 2013 British Open at Muirfield, emerged last year from a long slump in form, a comeback that peaked with a second place at the 2016 British Open.

"I haven't played at the level I expected to for a few years," he said.

"It wasn't until last year, kind of middle of last year around the British Open and so forth, that I really started to get my game back to where I wanted."

Now, however, he says he expects to play well, and to be in contention on a course he knows well and loves.

"I always love coming here. It's probably my favorite place in the world," he said.

"I do expect to play well and to compete here and come out on top more so than any golf course because of the opportunity to recover and utilize my short game, to salvage pars when I do hit a few wayward shots, which I've been known to."