Standing on the 18th tee with a two-shot lead in a championship he refused to imagine himself winning, Phil Mickelson took one last violent swing with a driver — the club that betrayed him 15 years earlier in the U.S. Open.

His tee shot Sunday in the PGA Championship at Kiawah Island landed only a few yards off the fairway, but it still nestled among the people — the gallery packed tightly between the ropes and a row of hospitality tents — screaming the name of their aging hero.

After Mickelson’s approach shot settled on the green, assuring the 50-year-old of becoming the oldest major champion in history, the crowd swallowed him up entirely.

Phil Mickelson, the people’s champion.

“It’s an incredible experience. I’ve never had something like that,” Mickelson said. “It was a little bit unnerving, but it was exceptionally awesome, too.”

Golf can be cruel to veteran, sentimental favorites. Ben Hogan at the 1955 U.S. Open. Greg Norman at the 1996 Masters and the British Open a dozen years later. And, perhaps most heartbreaking, 59-year-old Tom Watson at the 2009 British Open.

Mickelson, too, has had as many close calls as major victories — most of them at the U.S. Open, where he’s been runner-up six times. Winged Foot — where he gave away a one-shot lead on the 72nd hole in 2006 — wasn’t the first, or the last.

But now, the two biggest stars of their generation have a signature late-career win. Tiger Woods overcame four back surgeries, turmoil in his personal life and 11 years of frustration in major championships to win the Masters two years ago at age 43.

Mickelson — happy at home and injury-free — merely stretched the limits of what’s possible after a half-century on Earth.

“There’s no reason why I or anybody else can’t do it at a later age. It just takes a little more work,” Mickelson said.

Nine days earlier, Mickelson accepted a special exemption to play in the U.S. Open at Torrey Pines in his hometown of San Diego. Now he’s assured at least five more cracks at the lone major that has eluded him. The victory makes him exempt at the U.S. Open through 2025.

Already a Hall of Famer, Mickelson joined Nick Faldo and Lee Trevino as six-time major winners. Only 11 players have won more. If he somehow won another in his 50s, he’d match Arnold Palmer, Bobby Jones, Gene Sarazen, Sam Snead and Harry Vardon.

“I don’t know how to describe the feeling of excitement and fulfillment and accomplishment to do something when — you know, of this magnitude when very few people thought that I could,” Mickelson said.

The record will show Mickelson closed with a 1-over 73 for a two-shot win over Brooks Koepka (73) and Louis Oosthuizen (74). That doesn’t begin to describe the wild fluctuations of Sunday on the menacing Ocean Course, where Mickelson and Koepka hit shots that were both spectacular and shocking, sometimes on the same hole.

Between them, Mickelson and Koepka made 16 pars, 10 bogeys, nine birdies and one double bogey. Five of the first 10 holes had swings of two shots or more — and that didn’t include the par-3 fifth, when Mickelson holed out from a waste bunker with Koepka safely on the green.

Even with three bogeys in a five-hole stretch on the back nine, Mickelson hit enough good shots to avoid bigger numbers and hold off Koepka. Then came the bedlam on 18, where Mickelson and Koepka fought their way through the crowd to get to the green.

There were no fans at last year’s three major championships. Patrons returned to the Masters last month to cheer Hideki Matsuyama’s breakthrough win. But this was golf’s rowdiest gallery since before the COVID-19 pandemic, and it came at a time when the virus is receding in the U.S., with well over half of adults at least partially vaccinated.

Masks were rare among the crowd, which the PGA of America said was limited to 10,000 people a day. Fans pressed five-deep against the ropes, stumbled atop steep dunes and clambered into trees on the sprawling Ocean Course.

Golf, which surged in popularity last year as a sport with built-in social distancing, returned to something approaching normal, with fans celebrating an extraordinary champion.

“It was like the Phil that I remember watching just when I turned pro and it was great to see,” Oosthuizen said.

The records Mickelson shattered were numerous. Julius Boros for 53 years held the distinction of golf’s oldest major champion. He was 48 when he won the 1968 PGA Championship.

Mickelson became the first player in PGA Tour history to win tournaments 30 years apart. The first of his 45 titles was in 1991, when he was still a junior at Arizona State and Koepka was 8 months old.

Mickelson joined Woods — who sent a tweet of congratulations — among the 10 players who’ve won majors in three decades.

Lefty spent very little time talking to reporters before Sunday’s post-tournament news conference and refused to discuss what a win would mean to him. Instead, he pounded extra balls on the driving range — even on Sunday, he was rehearsing swing positions in between shots — and spent time meditating to recapture the mental sharpness he said he’d lost earlier this year.

“It’s been in Ohio as early as the mid-1850s at least, brought in as an ornamental plant because of its unique foliage and white flowers,” Gardner said. “It was actually planted in people’s landscaping, and it has been spreading.”

“Anybody who really thinks they can win on a Sunday is going to be feeling that pressure and the nerves,” said 49-year-old Padraig Harrington, who closed with a 69 to tie for fourth. “I’d say Phil is full to capacity, but that’s where he likes to live.”

This was Mickelson’s first major win with his brother, Tim, as his caddie. Could there be more?

“It’s very possible that this is the last tournament I ever win. Like if I’m being realistic,” Mickelson said. “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.”