Nobody has won a PGA Tour event and followed up by winning the U.S. Open the next week. Daniel Berger is confident enough in how he's playing to believe he can make a little history.

Berger, the 2014-15 rookie of the year, won his first PGA title Sunday in his 50th event, and the 23-year-old Floridian held off Phil Mickelson, Steve Stricker and Brooks Koepka by three strokes to finally hoist a trophy.

He's driving the ball down the middle of the fairway and has his putter working very well as he heads to Oakmont.

"When I played in the Masters for the first time, I think I finished 10th, five shots behind and didn't really play that great," Berger said Sunday night. "So, you know if I can go in there next week and play good, then obviously I have what it takes to get the W."

Only 11 have ever won a major after winning on tour, and Rory McIlroy was the last when he won the PGA Championship the week after taking the WGC-Bridgestone Invitational in 2014.

Mickelson certainly tried to chase down Berger after needling the man half his age during a three-hour delay for thunderstorms about having won rookie of the year without winning a tournament. Mickelson rolled in a long, beautiful birdie putt of 44 feet on No. 12 except Berger answered with three birdies over four holes on the back nine to clinch the victory.

"I just couldn't quite catch him, but I'm coming out of this week with a lot of positives and some good momentum," Mickelson said before heading to Oakmont.

Berger finished at 13-under 267. He became the 13th first-time winner on tour this season and took home the winner's check of $1.1 million in the 50th start of his career. He also became the fourth first-time winner at this event in the past six years and 10th overall in Memphis.

"To do that with so many great players, Hall of Famers behind me, it's something that I'll never forget and I just love the way I hung in there and was able to get it done," Berger said.

Mickelson and Stricker shot 67, and Koepka had a 66. Dustin Johnson had a 63, setting the back-nine record with a 29, to finish fifth at 9 under.

The thunderstorms slowed down the confident Berger, and only for a hole. He had hit only hit three shots when the horn sounded. Play finally resumed at 4 p.m., and Berger resumed by two-putting from 10 feet on No. 1 for bogey.

Berger already had finished second twice with a total of nine top 10s in his young career. He shook off the bogey by stringing together four straight pars with Koepka catching him atop the leaderboard at 9 under before bogeying No. 8.

He birdied Nos. 6 and 11 to make the turn at 11 under.

He stumbled on No. 10, two-putting from 10 feet again for bogey. Mickelson went to 9 under with two birdies on his first three holes on the back nine. Then, Mickelson's putter failed him as he just missed from 11 feet on No. 13 and 17 feet on No. 14 chasing his first win since the 2013 British Open.

Berger had no such issues as he rolled in putts of 8 feet on No. 12, the 32-footer on No. 14 — the same hole he put his tee shot into the water Saturday and double bogeyed — and a 22-footer on No. 15. That proved more than enough of a margin as Mickelson birdied the par-5 16th.

"It almost feels like U.S. Open came a week early to finish another second place," Mickelson said. "I'm excited to take the momentum that I built here in Memphis on a golf course I really enjoy and take it over to Oakmont and see if I can capture my first Open."

Johnson rebounded from a 73 by shooting the best round this week before heading to Oakmont. He chipped in for eagle on No. 16 from 16 feet and holed out from 22 feet on No. 18 to set the back-nine record. Johnson leaves feeling good about his own game heading to Pennsylvania.

"I played good all year," said Johnson, who's still looking for his first win this year. "I'm looking forward to next week."