Justin Rose produced a sensational finish at the FedEx St Jude Championship with six birdies in his last final eight holes to win a playoff against the US Open champion JJ Spaun.

The English golfer, who at 45 became the oldest European to win on the PGA Tour in the modern era, looked out of it after a bogey at the 12th dropped him to 12 under. That left Rose two off the pace with Tommy Fleetwood, the world No 1 Scottie Scheffler and Spaun ahead of him.

But four birdies from the 14th catapulted Rose to the top of the leaderboard and he just missed a 13-foot putt at the last to win outright. He produced two more birdies in three playoff holes, one a clutch effort after Spaun had holed from distance, with the second from 14ft after Spaun was half that distance away proving decisive as his opponent’s attempt to extend the contest raced past.

Justin Rose pulls off a fine approach from the edge of the water during his playoff against JJ Spaun. Photograph: Andy Lyons/Getty Images

“That was an amazing last 90 minutes. I never stopped believing,” Rose said. “I played unbelievable golf coming down the stretch and had so much fun with it. JJ dropped a bomb on me [at the second playoff hole], it was a lot of fun.

“When I bring my best I know I’m good enough to play against the best players in the world. This is going to be a fun one for us to celebrate.”

The playoff was packed with drama from the start as Rose – who barely cleared the lake with his drive – gave himself an identical 13-foot putt to the one he missed to win the tournament, but it burned the edge of the cup. Playing the hole again, Rose hit to eight feet but Spaun recreated his US Open final green heroics with a monster birdie, forcing the Englishman to hold his nerve.

The hole location was re-cut for the third attempt to avoid shadows and Spaun duly hit it to seven feet but Rose, who had lost his previous four playoffs including, like Spaun, to Rory McIlroy this year, dramatically turned the tables by holing his 14ft birdie and Spaun fired past.

Rose’s joy meant more heartbreak for Fleetwood, who blew another chance to break his PGA Tour duck at the 162nd attempt with a poor finish. The Ryder Cup teammates had holidayed together in Portugal last week, but failed to spark each other into life in the final group.

Fleetwood did not make a birdie until holing his longest putt of the week from 33ft at the 12th to put him back in a share of the lead. Birdies at the 13th and 15th edged him two in front on 16 under, but as he was escaping with a par after chipping across and off the green with his third at the 16th, Spaun was tying the lead with a birdie at 17.

Tommy Fleetwood hits out of a fairway bunker on the 18th hole during the final round. Photograph: Andy Lyons/Getty Images

Fleetwood’s weak attempt at a 7ft par putt at the 17th never threatened and needing a birdie at the last just to make a playoff, he drove into a bunker and missed the green with his approach.

“I’m obviously going to be disappointed. There’s a lot of positives to take but it won’t feel like that right now,” said Fleetwood, whose 29th top-five PGA Tour finish is 11 more than any other player without a win over the last 40 years. I’m just going to look at what I feel like I could have done and how close it was.”

Scheffler, without his regular caddie Ted Scott who returned home due to a family emergency, finished a shot outside the playoff after two birdies in his final three holes.

Jordan Spieth’s Ryder Cup hopes were dealt a blow after he dropped out of the top 50 of FedEx Cup rankings and missed the cut for next week’s penultimate event after dumping his approach to the last into the water, ending his season and, at 27th in the United States’ rankings, likely his Ryder Cup hopes.