For the second day running the South African produced the day’s moment of magic – a drive to five feet on the par four 16th setting up a decisive eagle as he shot a round of 66 for a 19 under par total.
That followed a miraculous snap-hook wedge from the trees at the fifth on Saturday, where the resulting birdie set up a third round 68 after a shaky start.
“It was a great day, a great week, and it’s another trophy to put in the cupboard,” said Grace. “I’m going to thank Callaway again – that driver again on 16 to four feet; without that it wouldn’t be possible.
“That wedge on the fifth hole, that was a shot that you want to hit but you don’t always manage it.
“The form has been there, I played great and I managed to get in on top.”
Victory represents Grace’s second of the 2015 Race to Dubai, having already captured the Alfred Dunhill Championship on home soil.
Grace and Warren both started the day in a four-way tie for the lead with Emiliano Grillo and Bernd Wiesberger, but a host of other players also mounted challenges on a dramatic last day at Doha Golf Club.
Warren was first to show his hand when he birdied the first from ten feet and second from 15 feet, but his challenge stalled when he double bogeyed the short eighth after his tee shot found the water.
Wiesberger had got off to a poor start with bogeys at the second and third, but holed along birdie efforts at the fifth and seventh and headed for home with three straight gains to take control of the tournament.
France’s Grégory Bourdy went out in a six under 30, but his title bid ended when he failed to get up-and-down on the 15th, while Korea’s Byeong-hun An also shot 65, and might have caused a few nerves to jangle among those in the groups behind him had his birdie putt at the last not lipped out.
Warren recovered with birdies at the ninth and tenth, while Grace went ten holes without a birdie before holing from ten feet at the 12th.
Grace gave a fist pump after converting from 15 feet at the 14th, but Warren again dug deep with gains of his own at the 13th and 14th.
Grace’s moment of magic at 16 looked to have been enough, but Warren birdied there and holed an eight footer at the short next after a brilliant tee shot, but could not match Grace’s birdie at the last after the South African pitched to three feet.
“This morning, I woke up, I went through a little bit of the previous videos of when I won just to try to get me in the right frame of mind and it worked,” added Grace. “It was a nice way to wake up.
“The Middle East is one of the places I’ve always wanted to win. I’ve thought my game suits these type of golf courses, and I play well when I come here.
“These are big now, so this is one of the wins that’s really putting me back on the map now. I think I’ll be in the top 50 or just outside [on the Official World Golf Ranking].
“These are the things that we need as golfers to push us to the next level – it’s just nice that I could do it at a place like this and in a special way like this.”
Warren’s 67 saw him finish alone in second on 18 under, with Wiesberger third after a 68 and Eddie Pepperell’s inward 32 giving him solo fourth after a 67. An, Bourdy and Grillo were tied for fifth on 15 under.