Justin Thomas' caddie finally got his Major memento after years of being snubbed by old employer Phil Mickelson

• Justin Thomas won the PGA Championship on Sunday with caddie Jim "Bones" Mackay on the bag.
• Mackay had worked for Phil Mickelson for decades before their 2017 breakup. In that time, Mackay never got to keep the 18th flags from Phil's victories, as is tradition for caddies.

Justin Thomas played a masterful 18 holes of golf on Sunday at Southern Hills Country Club in Tulsa, Oklahoma, doing just enough to reach a playoff for the PGA Championship after starting the day seven strokes back of the lead.

After a three-hole playoff against Will Zalatoris, Thomas was crowned champion, taking the second major win of his career, having previously won the same event in 2017.

With Thomas through every swing and putt of his championship weekend was caddie Jim "Bones" Mackay.

Mackay, who worked for decades with Phil Mickelson before picking up Thomas' bag full-time in 2021, played a key role in getting Thomas across the finish line, giving his player a little bit of necessary straight talk on Saturday night ahead of what proved to be the major-winning round.

"I'm fully confident in saying that I wouldn't be standing here if he didn't give me that — wasn't necessarily a speech, but a talk, if you will," Thomas said after his round.

"I just needed to let some steam out. I didn't need to bring my frustration and anger home with me. I didn't need to leave the golf course in a negative frame of mind. I just went down — I played pretty well yesterday for shooting 4-over, and I felt like I'd played terrible. And he was just like, Dude, you've got to be stop being so hard on yourself. You're in contention every single week we're playing."

For Mackay, the win was especially meaningful, as it was his first major win as a caddie since leaving Mickelson's bag.

According to a new biography of Mickelson by golf writer Alan Shipnuck, "Phil: The Rip-Roaring (and Unauthorized!) Biography of Golf's Most Colorful Superstar," Mickelson's treatment of Bones after wins was one of the sources of their strained relationship.

It's tradition for caddies to keep the 18th flag from their wins on the PGA Tour, but according to Shipnuck, Mickelson would keep the flags as souvenirs for his own family, rather than pass them along to his caddie.

Per Shipnuck's book:

"That's a giant fuck-you to a caddie," says someone very close to Mackay. "When Phil wins the Masters, he gets the green jacket, the trophy, the big check, all the glory. He had to take the flags, too? Every other caddie who has ever won the Masters got to keep the eighteenth-hole flag. For Phil not to follow tradition was hugely disrespectful." During the week of the Phoenix Open, the Mackays would often host dinner parties for players and caddies at their home, and a frequent question was "Where are all the flags?" It nettled Mackay in a way that is hard for any outsider to understand.

While Mickelson would eventually send Bones some of the 18th flags from their wins together in the midst of their breakup, "Phil autographed them in comically large letters, which Mackay felt disfigured the keepsakes," according to Shipnuck's book.

On Sunday at the PGA Championship after Thomas' win, Bones got a flag all his own.

After the win, Mackay was clearly emotional.

"If I was ever going to caddie again, this was the time, and without question, this was the player," Mackay said. "My wife will tell you — the person I said from the get-go that I would leave for, if the opportunity arose, was Justin Thomas."

For Mackay, the jump to Thomas' bag has worked out swimmingly.

If Thomas keeps up his hot run of play, there could be many more flags in Bones' future.