Irwin recovered from a front-nine mental meltdown that included a ball tossed into a creek in anger and a whiff on a tap-in - reminiscent of his gaffe at the 1983 British Open - to win his first Champions Tour title of the season Sunday with a birdie on the second playoff hole over Tom Watson.
'Call it an airball,' Irwin said afterward, seemingly amazed that he won the tournament in such an unusual way. 'I would never have believed anything like this would happen. What a day.'
Watson was amazed, too.
'It's just stupid,' Watson said of his playing partner's bumble. 'If he can whiff it from inches out and still win the tournament, that shows he's the best on the tour.'
It was the 37th Champions Tour win for Irwin, who will be 58 next month. Last year Irwin, who won three U.S. Opens, became the oldest player on tour to win the money title.
Watson won the 1983 British Open, beating Irwin by a stroke. 'I guess he got me back today,' Watson said.
'The '83 British Open was another one that constituted an airball,' Irwin said. 'That one was just bad judgment. Today was just being upset.'
Irwin and Watson both shot 1-over 73 in the final round at The Hills Country Club on Sunday and finished at 8-under 208. They both birdied the 18th hole of regulation, snapping what had been a four-way tie with Tom Kite and Bob Gilder.
Irwin and Watson both parred No. 18 on the first playoff hole, but Watson nearly won it when his bunker shot for birdie lipped out. Then they headed back to the par-3 16th, the course's signature waterfall hole.
Watson's birdie attempt curled short about two inches out. Irwin then sank an 8-footer for the win.
'I thought I made my putt,' Watson said. 'It really banked right.'
It was the first Champions Tour event of the season to go to a playoff, and Irwin became the 11th different winner in 11 tour events this year.
Irwin could have won it in regulation if not for his four-hole collapse early in the round. He was tied with Kite at 10-under after two holes before a tee shot into a clump of pampas grass forced him to hit left-handed. He had a double bogey to fall two strokes back. It made him so mad he threw his ball into the greenside creek.
It got worse on No. 6 when Irwin whiffed a backhanded swipe at a six-inch tap-in. To make matters worse, he then stabbed at the ball again, only to top it about two inches. When he finally settled down and put it in the cup, the triple bogey knocked Irwin from one shot off the lead to four back.
Visibly angry, Irwin started tossing his clubs, groaning about his mis-hits. He was fading fast before a birdie on the 10th hole calmed him down.
'I hit a boiling point,' Irwin said. 'I got carried away ... It's not that I've got the yips. I just had to back off.'
Irwin was four strokes off the lead with five holes to play but got back in it with birdies on Nos. 14, 17 and 18 to catch Watson and force the playoff.
'I knew there would be a birdie in the group,' Irwin said of the final hole of regulation.
Kite, who played college golf at the University of Texas and still lives in the Austin area, had the hometown crowd behind him during all three rounds. But it couldn't carry him to his first professional win in his home state. He held a two-stroke lead with five holes to go but bogeyed 14 and 17 to drop into the four-way tie.
He continued his self-destruction on the final hole by spraying shots into the rough, behind a scoreboard and into a bunker on his way to a bogey, costing him a chance to make the playoff.
'I feel bad,' Kite said. 'I feel like I let the whole town down.'