If you’re on the wrong side of 50, you’re probably walking with a spring in your step today courtesy of Phil Mickelson.

Mickelson, less than a month shy of his 51st birthday, became golf’s oldest major champion with an emphatic victory march at the US PGA Championship at Kiawah Island today.

The evergreen left-hander could only manage a one-over-par 73 to finish at six under, but it was enough for a two-stroke win over Brooks Koepka and Louis Oosthuizen, both of whom frittered multiple chances to play spoiler.

No fewer than 17 years after his first of three green jackets at the Masters and 16 years since his first Wanamaker Trophy, his sixth major crown came a remarkable eight years after his most recent, the 2013 Open Championship.

And it was absolutely the least expected, his odds having been in excess of 250-1 at most betting agencies pre-tournament.

In becoming the first World Golf Hall of Fame member to win a major championship after their induction, he also wiped out fellow American Julius Boros from the record books – the three-time major champ the previous oldest winner having won the 1968 PGA Championship at age 48.

“I hope this inspires a lot of people … this is an incredible feeling,” Mickelson said.

“I believed it was possible but everything was saying it wasn’t.

“My desire to play is the same (as ever). I’ve never been motivated externally, I’ve always been intrinsically motivated to play against the best at the highest level.

“The belief I could do it motivated me. I just couldn’t see why it couldn’t be done.

“I don’t know how to describe the feeling of fulfilment (and) accomplishment of this magnitude when so few people thought I could do it.

“It’s a moment I’ll cherish my entire life.”

Mickelson was asked what it would like for history now to forever more view him as an “old man”, courtesy of his new record.

“It’s possible it’s the last tournament I win, if I’m realistic,” he quickly reflected.

“But it’s also possible I’ve had a breakthrough in my focus and I could go on a little run.

“The point is it can be done. You just have to work a little harder.

“I worked harder physically to be able to practise as hard as I need to.

“It might take a little harder effort to maintain (yourself) physically, or the skills, but gosh is it worth the effort.”

On a day when great scores were out on the Ocean Course – Abraham Ancer posted a 65, Justin Rose a 67 and Matt Jones a 68 – all those immediately chasing Mickelson found reverse gear at crucial moments.

In the final pairing alone, there were no fewer than five times in the first 11 holes when Mickelson and Koepka had minimum two-shot swings as the leaderboard swung violently.

But when they turned on to the back nine, Mickelson’s perfectly struck 7-iron on the 10th hole set up what proved a winning break.

Koepka dropped three shots in four holes, while Oosthuizen bogeyed the 10th and took a sloppy double on the 13th right when the pressure gauge could have been cranked.

By the time Mickelson cranked enormous drives on the 15th and 16th, his edge was insurmountable and he found cruise control coming in.

Mickelson said he’d gone into a media-free bubble during the tournament to “stay present”.

His caddie, brother Tim, said it was the most focused he’d ever seen Phil, yet still had to challenge his older brother during the round.

“Probably 200 times I told him to keep his mind quiet,” Tim said.

Phil praised his brother and all those around him, including Australian coach Andrew Getson.

“I’ve not let myself think about the result until now,” Phil said.

“I was just trying to stay in the present, wasn’t watching TV, getting on my phone, just trying to quieten things down because my thoughts would be racing.

“I believed for a long time that I could get back to this level.

“I’ve had a few breakthroughs on being able to stay present and focused, because physically I was playing as well and striking it as well as ever.

“So there was doubt, for sure ...

“I worked harder, that’s the deal.

“I believed I could do this, but until this week I haven’t been able to prove it to everyone.”

Mickelson, who joined Sam Snead, Ray Floyd and Davis Love as the only players to have won in four different decades on the US PGA Tour, described Getson’s role in rebuilding his confidence to his glory days as “invaluable”.

“Andrew is a tremendous instructor because of his ability to simplify it (golf),” Mickelson said.

“He has helped get my swing on plane … doesn’t cloud my head with a lot of things and he’s able to keep me on track right away if I make a few errors.

“His guidance has been invaluable … he’s helped me get my ball striking back.”

Mickelson also paid tribute to legendary Tom Watson who made a run as far as a playoff aged 59 during the 2009 Open Championship.

“That was one of the greatest sporting performances. It’s inspiring to see people like that do it,” he said.

“I hope it inspires people to put in the work. There’s no reason you can’t, you just have to do that work.

“There’s no reason the game of golf can’t be a game for lifetime. If you take care of your body … you can work out the right way to play golf for a lifetime and I appreciate that.”

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