"It's awesome. He's been so close so many times. I don't feel like it's real," Boyd said. "It will be a good wedding."
After becoming the seventh player to take his first career PGA Tour triumph in New Orleans since 2002, Dufner called it a "great wedding present for both of us."
"It helps with paying for the wedding, obviously," added Dufner, who earned $1,152,000. "They're a little more expensive than I thought or had imagined. ... It'll be a big celebration not only for our marriage but also for my first victory out on the Tour."
Luke Donald shot a 67 to finish third at 17 under, and move past Rory McIlroy for the No. 1 ranking in the world.
"That's a nice consolation," Donald said, adding that the rankings could change again when he takes next week off and McIlroy is expected to play. "It's been going back and forth a little bit. Rory's turn next week. ... It was a little bit of a motivation to try and play well today."
Defending Zurich Classic champ Bubba Watson, playing for the first time since a life-changing win at the Masters over Easter weekend, entered the final round eight shots off the lead. He was unable to mount a charge after bogeys on his first two holes. He wound up tied for 18th at 11 under, a solid outing by most standards, but one of his worst finishes of the year.
"All in all, pretty good week being tired, coming back for the first time after winning the Masters, all this different media attention," Watson said. "It's something you got to get used to. (It) wears on you, tires you out. Somehow I finished — I'm in the top 20. A lot of guys wished they did that."
Els and Dufner were tied at 19 under after 11 holes. Els made par on each of his final seven holes of regulation. Dufner made par on his final eight, none more difficult than on 16, when he hit into water, but salvaged par with a 44-foot putt.
Els' 17-foot birdie putt on 18 missed by about an inch, opening the door for Dufner to win in regulation if he could birdie the 585-yard hole to cap his fourth round.
While Els was on the practice green preparing for a possible playoff, Dufner chipped on to set up a potential winning putt from 10 1/2 feet.
Although he could not convert, pushing the ball about a foot past the right edge of the hole, he made up for it in the playoff.
Now it's on to his wedding in Auburn, Ala., though honeymoon plans are a little unclear and may be on hold until after the British Open.
"The honeymoon is going to be at The Players Championship," Dufner joked about the event in two weeks at TPC Sawgrass. "They got an island green. Pretty cool event."