Day to face Dubuisson in final
Australia's Jason Day will take on Victor Dubuisson of France in the WGC-Accenture Match Play final on Sunday.
Day beat American Rickie Fowler 3&2 at Dove Mountain and will climb to sixth in the ranking if he loses this evening's final, or fourth with a victory.
The 26-year-old looked to be cruising to victory when he led by three holes with seven to play, but lost the next two to give Fowler hope of mounting a successful comeback.
However, Fowler then bogeyed the 15th after chipping across the green and into a drainage ditch and the match came to an anti-climactic end as the American three-putted the 16th from six feet.
"I knew Jason was going to be tough," Fowler told Sky Sports. "He made quite a few good putts, he didn't give me a whole lot. He missed a par putt on 12 but other than that he played solid all day.
"On 15 I was in a tough position, I couldn't really make anything of it and 16 was a complete mis-read. Jason played well and he's going to be tough to beat this afternoon."
Day added: "I felt like I had a really good chance of having a shot of winning this week and I am really looking forward to it. I played some nice golf today so hopefully I can keep it going in the final."
Day will face either Dubuisson in the final.
Els had been three up after just four holes as Dubuisson made a shaky start, but the Turkish Airlines Open winner made a crucial par save from 15ft on the seventh to avoid going further behind and then birdied three of the next four holes to get back on level terms.
A par on the 12th was enough to give Dubuisson his first lead of the day as the match began to swing back and forth, the Frenchman making a mess of the 14th but holing from six feet for a birdie on the 15th to get back in front.
Els then holed from long range on the 16th to make it all square once more, but the 2012 Open champion bogeyed the last after hitting his approach into a greenside bunker to send Dubuisson into the final.
The 23-year-old is now guaranteed at least £545,000, which effectively secures his Ryder Cup debut at Gleneagles in September.
Dubuisson put his bad start down to being nervous about taking on his idol Els in his first WGC event, telling Sky Sports: "It feels great (to win), especially because this morning I was not feeling comfortable.
"I didn't sleep very well and when I arrived at the course I realised I was in the semi-final of a World Golf Championship event against Ernie Els.
"I am a big fan of him, always watching him winning majors, and I was not as comfortable as the round before. That's why I had a poor start.
"I made three or four very bad shots and then I tried to focus again on my game and knew I had to play my best golf. That's what I did and proved my mentality is very solid."