Zach Johnson edged out Jason Dufner at Colonial on Sunday - despite a freak incident on the 18th green.

Leading by three at the Crowne Plaza Invitational as he and Dufner stood over their putts at the 18th, Johnson failed to replace his ball to its original position after marking it in order for Dufner to make his putt first. He was handed a two-stroke penalty for the rules breach, but not before making a five-foot putt for par to hold on for a one-shot victory.

When Johnson made that putt on the 18th he had no idea that it was as important as it turned out to be, believing himself to be three shots clear at that point. Nor did Dufner know that his earlier birdie attempt was in fact a great chance to force a play-off.

It was a bizarre situation on a day set up for Johnson by two crucial mistakes made by his opponent.

Leading by one overnight, Dufner, the hot favourite to pick up his third PGA Tour title in the space of five weeks, first made a big mistake at the ninth - a double bogey after finding the water with his approach to the green.

Even worse was to come at the 15th, however, when Dufner's approach hit the left side of the green and rolled into a ditch, leading to a triple bogey that suddenly put him four strokes back of Johnson.

Johnson bogeyed the 16th to cut his lead down to three, but that was how it stayed till the drama-filled 18th. Johnson eventually finished on 12 under, one stroke clear of Dufner.

"I'm going to focus on the positives, because I hit a really solid putt and it's a good thing I made it," Johnson said. "No harm, no foul. It was my fault.

"In some respects, I kind of feel like I took down a lion," Johnson said about beating Dufner in what was essentially a match-play shoot-out between the two on the final day. "He's been at the top of his game."

Dufner had no excuses about his own performance, insisting that fatigue did not play a role.

"Pretty good run, today obviously a little disappointing to play that poorly and not kind of a chance there at the end," he said. "I feel pretty good actually, I just played really poorly today."

Tommy Gainey finished a distant third on seven under after a 67, one shot better than Jim Furyk, who had a 68.

Golf 365