Paul Casey suffered a nightmare final round as Xander Schauffele won the Tour Championship and runner-up Justin Thomas claimed the FedEx Cup title and 10million US dollars bonus.
Casey began the day with a two-shot lead and in pole position to celebrate the recent birth of his second child by winning his first PGA Tour title since 2009 and the £7.4million payday.
However, the 40-year-old could only card a closing three-over-par 73 at East Lake to finish nine under par, three shots behind 23-year-old rookie Schauffele, whose 68 left him a shot ahead of compatriot Thomas.
Any of the 30 players in the field theoretically had a chance of the massive payout, but only the top five in the standings were assured of doing so by claiming the 1.53million dollars (£1.1million) first prize in Atlanta.
Open champion Jordan Spieth began the week with a 200-point lead over Thomas, with world number one Dustin Johnson, Marc Leishman and Jon Rahm the other players in control of their own destiny.
As the situation fluctuated on a hole-by-hole basis in the final round, Spieth was projected to win the FedEx Cup after holing his approach to the 10th for an eagle and tapping in for birdie on the 13th.
But a bogey on the 15th effectively ended his chances as Thomas moved into a share of the lead with birdies on the 16th and 17th, only for Schauffele to hold his nerve and birdie the last to win.
Thomas, whose five wins this season included a maiden major title in the US PGA Championship, told Sky Sports: " I'm bummed to not be in a play-off and have a chance to win but that was a gutsy birdie Xander made on 18.
"I was trying to win a golf tournament, winning the FedEx Cup is a great bonus.
"It's a feeling I've never experienced before, it's just weird because it didn't come with winning the golf tournament so it's hard to fully appreciate it. It's a tremendous honour and I'm really excited to have my name on the trophy."
Schauffele won 149,000 US dollars on the Web.com Tour last season, but collected more than 3.5million dollars on Sunday.
"It feels awesome," he said. "(I'm) a little speechless.
"I thought I'd missed the putt to win the tournament and fortunately it just lipped in. I was very relaxed for most of the day and got really nervous when I saw the leaderboard on 16."
Spieth had to settle for a tie for seventh but admitted his good friend Thomas was a deserving winner of the FedEx Cup title he won himself in 2015.
" It was a great season, if I could repeat if every year for the rest of my career I certainly would," Spieth said "I knew after the 10th hole that I could win the FedEx Cup and they just didn't quite go my way.
" I think it's rightfully so that he (Thomas) wins the season-long race this year. Five wins with a major championship and you'd like the FedEx Cup to go to the most deserving player for the entire year and I think that's him.
"I almost cheated my way into winning the FedEx Cup when he really deserved it. I'm very happy for him - I'm fortunate to have done it and it's really something else."