Perhaps, just as important, is the fact he now leads the FedEx Cup with just the Tour Championship to play. On form, he must be the favourite to take home the $10 million bonus for winning the season-long series.

Johnson shot a final round of five-under 67 at Crooked Stick in Carmel, Indiana, to get to 23 under, three strokes clear of Englishman Paul Casey. Casey is now 33 under for his last two tournaments and has been runner-up in both, having been overhauled by a fast-finishing Rory McIlroy at the Deutsche Bank Championship last week.

The final round at Crooked Stick became a race in two as the final pairing of Johnson and Casey went head-to-head. When Casey rolled in an eagle from 25 feet at the par-5 15th hole, it put the final result in some doubt. But Johnson’s reply was swift and decisive, grabbing an eagle of his own moments later to maintain his three-stroke advantage.

Dustin Johnson poses with the BMW Championship trophies. PHOTO: Scott Halleran/Getty Images.

From there, Johnson needed only to make pars to get the win as Casey left himself long putts for birdies that failed to drop.

This victory follows Johnson’s breakthrough major win at the US Open and the WGC-Bridgestone Invitational, which places him alongside World No.1 Jason Day for the most wins on the PGA Tour this season.

FINAL LEADERBOARD  |   FEDEX CUP STANDINGS

Where Johnson was once often criticised for his mental frailties in the final round of big events, he has started to gain a reputation as a strong closer of tournaments.

“The more I practice, the more I’m in the situation, the more I know what to do and what to expect in the situations and kind of know what shots that I can hit and not to hit and I like it,” he said.

“I enjoy being in the hunt and having to hit really good shots when you need to and I felt like the last few times I’ve been there I’ve hit some great golf shots to finish it off.”

Johnson head to East Lake and the Tour Championship as the FedEx Cup leader, while Barclays winner Patrick Reed is second.

Adam Scott has been a model of consistency during the play-off series. PHOTO: Stacy Revere/Getty Images.

Adam Scott has been rock solid without being spectacular during these play-offs. He has finished no worse than T4 in three events now, with his tie for fourth at Crooked Stick elevating him to third position in the FedEx Cup standings, just ahead of Day, who withdrew nine holes into the final round after a sustaining a back injury.

Whether Day is a starter at the Tour Championship in a fortnight remains to be seen but the opportunity to pocket $10 million might be enough to quell the pain.

Victorian pair Marc Leishman (67) and Aaron Baddeley (76) finished 68th and 69th respectively on the FedEx Cup standing to miss out on the top-30 advancing to the Tour Championship.