They gave him his first European Tour win.
Haig, a 20-year-old South African, birdied No. 18 at Blue Canyon to make a three-way playoff with Richard Sterne and Oliver Wilson, then returned to the par-4 and birdied it again to walk away a winner Sunday at the Johnnie Walker Classic.
He shot his second consecutive 2-under 70 in the final round and came from two shots down -- clinching the win with a 10-foot putt on the first extra hole.
'It feels absolutely amazing,' Haig gushed. 'I didn't think this would be possible, but after shooting 64 in the second round I knew I was hitting the ball well enough to win.'
Sterne, the overnight leader after twice tying the course record with consecutive 64s, managed only an even-par 72 on Sunday and bogeyed the 17th hole to fall into a tie.
Wilson, the second-round leader, closed with a 1-under 71 and made the playoff with a bogey-free back nine that included two birdies.
The trio finished 72 holes knotted at 13-under-par 275.
Haig moved into the clubhouse lead with a virtuoso finish at the 18th, clearing trees with his lob wedge on a tough 100-yard approach shot and knocking it within three feet to set up his closing birdie.
'One of the best shots I've ever hit,' he declared.
Wilson and Sterne also had birdie putts at the 72nd hole with a chance to edge Haig in regulation, but neither could get their try to drop.
With several of the word's best golfers safely out of the picture -- Retief Goosen, Ernie Els, Colin Montgomerie and Mike Weir all finished within five shots -- the co-leaders headed back to the 18th for their playoff.
All three reached the green in regulation, but Wilson missed a 20-foot putt and Sterne botched a 10-footer to open the door for Haig, who rolled in his own 10-foot try for the win.
'What a feeling. I am struggling to [put] it into words,' Haig said.
For the others in the playoff, there was disappointment.
Wilson played his back nine flawlessly, but had back-to-back bogeys on the front and went out in 37 -- his worst front-nine score this week by three shots.
'I had my chances but didn't take them,' said Wilson. 'I hit great tee shots at the 18th in regulation play and in the playoff but was disappointed not to be putting from less than 20 feet either time.'
Sterne was unable to enjoy the fruits of his back-to-back record-tying rounds. He had an early bogey at the par-4 third, then strung together 11 pars and two birdies before stumbling to another bogey at the par-3 17th.
'It was close, but what can I do?' said Sterne. 'I played my best but it didn't go the way I wanted. I am disappointed but it's great for Anton.'
Goosen, the 2002 champion, shot a final-round 70 and finished three shots behind the leaders at 10-under 278. Weir had a 67 and was a stroke further back at 9-under 279.
Two-time champion Els (70) and Montgomerie (71) tied for sixth place at 8- under 280. They were joined by David Frost (69) and Gaurav Ghei, who became the latest player to match the course record of 64.