Day, seeking his first PGA Tour victory since the Players Championship in May last year, missed a four-foot par putt on the first play-off hole to give Horschel the victory. It was a shock miss from close range for Day, who had previously made 278 of 291 putts inside five feet (95.5 percent) this season. It was Day’s only three-putt for the tournament.

Earlier, Day closed with a two under 68 to reach 12 under which was matched by Horschel’s one under 69 that included a 60-foot birdie putt that dropped on the 14th hole.

Day had a chance to finish at 13 under but his 18-foot birdie putt on the 72nd hole burned the edge of the cup and he cleaned up for par.

“Obviously when you're in position like this you got to go for it,” said Day of his birdie putt in the play-off.

“That first putt was great. I hit a great putt and just a tad too hard. If it was probably maybe a foot slower it probably would have turned in there nicely and gone in the hole. But that's what you got to do if you want to win, you got to take risks. If you don't take the risks, you'll never win.

Jason Day celebrates a chip-in on the 15th hole during the final round. PHOTO: Drew Hallowell/Getty Images.

“I only had one Top-10 (this season) up until this point. To be able to play the way I did today, I played some good, solid golf. Obviously, once again, it's a little disappointing but it's not the first tournament I'm going to lose. I've lost plenty of other ones beforehand and I'll lose plenty more in the future.

“I got to try to get better from this experience and I feel good about my game. Everything is coming along nicely.

“I’ve got to work a little bit more on the overall game of things and I think if that happens, then I should be in pretty good form coming into the Majors.”

For Horschel the win was a relief. Having recorded four consecutive missed cuts prior to the Byron Nelson, he was at long odds to turn his game around so quickly. But he did and he grabbed his first PGA Tour win since 2014, when he won the season-long FedEx Cup title and Tour Championship.

To the victor goes the spoils. Horschel holds a trophy for the first time since 2014. PHOTO: Drew Hallowell/Getty Images.

Horschel said he sympathised with Day missing his short putt.

“Fortunately, he missed a short putt,” Horschel said. “I missed a short putt not too long ago at McGladrey to miss a playoff. I know that feeling.

“I told Jason it's not the way I wanted to win. I know it's not the way he wants me to win. We want to earn it with a birdie.

“But he's a tough competitor and neither of us had our great game today and we just all battled it out and I was fortunate to come out on top.”