Starting the day four shots off the pace, Fox immediately closed the gap with a birdie on the first hole to move to 11-under.
A bogey on the third saw Fox drop back, only to make back-to-back birdies on the fourth and fifth. That birdie at the fifth could have been so much more, though, as Fox came narrowly close to chipping in for eagle from the rough.
Fox’s inconsistency on the front nine continued with another bogey at the par-three sixth, only to make another shot back with a birdie on the seventh and move to 12-under.
Meanwhile, MacIntyre drained birdies on the seventh and eighth to move to 16-under, before Fox’s front nine finished with a bogey on the ninth, and dropped him five shots off the pace.
Needing a charge on the back nine, Fox began with a bogey on the 10th, and dropped back to even par for his final round, and dropped into a share of eighth place.
Even as Fox sunk a birdie on the 12th, MacIntyre did the same at 11, and moved even further clear of the field at 17-under.
From a share of eighth, another birdie on the 13th moved Fox up into fourth by climbing higher to 12-under, helped when MacIntyre bogeyed the 12th to drop back to four shots in front of the chasing pack.
But a bogey on the 14th, Fox’s fifth of the day, ultimately spelt the end of the Kiwi’s charge for victory, as par on the 15th left him four shots back with three holes left to play.
And after three straight pars from the 15th to the 17th, Fox finished with one last bogey on the 18th, dropping back to even par for the final round, and a tie for seventh with USA’s Maverick McNealy, and Mackenzie Hughes of Canada.
Despite a strong final day from the likes of Rory McIlroy (13-under), MacIntyre’s biggest challenge came from Griffin, and wasn’t able to seal his win until the 18th.
Holding a one shot lead on the final hole, and as fog closed in, MacIntyre watched Griffin miss a birdie putt for a share of first, and left the Scot with two putts up his sleeve to take victory.
And after missing his first attempt, MacIntyre didn’t falter on the second, and celebrated his first victory on the PGA Tour.