Who saw that coming?
The bookies made Phil Mickelson a 300/1 outsider before a shot had been hit on Thursday morning.
History said he might be a five-time Major Champion, but that was all in the past.
Five fiftysomethings had led a Major with 18 holes to play, but Father Time had caught up with every single one of them - no-one in his sixth decade had actually claimed one of the four titles that define a career.
It was not only history, but recent form that went against notions that the Californian could lift the trophy - he hadn't finished in the top 20 on the PGA Tour in nearly a year.
But over four thrilling days, Mickelson defied all those odds.
He had started the week ranked alongside James Braid, JH Taylor, Byron Nelson, Peter Thomson and Severiano Ballesteros as a five-time Major winner, he ended it sat alongside Nick Faldo and Lee Trevino with half a dozen to his name - only 11 men have won more.
Let's take a look at what Mickelson said about his victory, and also what the rest of the world thought of it via social media.
Mickelson on the final moments walking up to the 18th green:
"It was an incredible experience. I've never had something like that. It was a little bit unnerving, but it was exceptionally awesome, too. Kind of a special moment, I'll always be appreciative of the way that people here have supported me and the entire tournament."
On what keeps him competitive:
"I just love this game of golf, and I love what I do, and I love the challenge of competing against such great players.
"I believed for a long time that I could play at this level again. I didn't see why I couldn't, but I wasn't executing the way I believed I could. It's very exciting because I've had a few breakthroughs on being able to stay more present, being able to stay more focused, and physically I'm striking it and playing as well as I ever have.
"But, although I believed it, until I actually did it, there was a lot of doubt, for sure."
On putting the achievement into perspective:
"It's certainly one of the moments I'll cherish my entire life. I don't know how to describe the feeling of excitement and fulfilment and accomplishment to do something of this magnitude when very few people thought that I could. The people that believed in me, my wife, Amy, Tim and (coach) Andrew Getson, those are the people that continued to inspire me to get the best out of me."
On the possibility of a fiftysomething winning a Major:
"I didn't see why not. I mean, I thought the 2009 Open Championship performance by Tom Watson was one of the greatest sporting performances, and he hit a perfect second shot (at the last), too. He couldn't land it any better and it still went over. It was one of the greatest performances in the sport. And it's inspiring to see people like that do it.
"I hope that this inspires someone to just put in that little extra work, because first of all, there's no reason why you can't accomplish your goals at an older age. It just takes a little more work."
On the future:
"So it's very possible that this is the last tournament I ever win, like if I'm being realistic. But it's also very possible that I may have had a little bit of a breakthrough in some of my focus and maybe I go on a little bit of a run, I don't know. But the point is that there's no reason why I or anybody else can't do it at a later age. It just takes a little bit more work."
On besting final round partner Brooks Koepka:
"What an incredible competitor and tough player Brooks Koepka is, and to have a chance to play in the final group with him was an exceptional honour. It's been really fun for me to see his development. I remember playing a practice round with him in 2013 at Oak Hill PGA Championship, first time we ever played together, and seeing the way his game has developed, and what a tough player he is. It was a really difficult task for me to go head-to-head and come out on top and I'm appreciative of the opportunity."
On the birdie he made from a bunker at the fifth in the final round:
"Certainly it was a momentum builder. It was a little bit early in the round to start jumping ahead because, you know, so much can happen. It was only the fifth hole but that was a big momentum thing. Biggest thing was getting it up-and-down. I just didn't want to throw away another shot and I had fought hard to keep the round in check and I was still 1-over through four. So I just needed to get that up-and-down. To have it go in was a bonus but I knew I had a lot of work ahead."
On what he has sacrificed to get back into shape:
"Food! Yeah, I've got to eat a lot less, but I've got to eat better. I just can't eat as much and I have to let my body kind of recover. But it's also been a blessing for me because I feel better and I don't have inflammation and I wake up feeling good.
It's been a sacrifice worth making."