Luke Donald raises his putter after winning the Transitions golf tournament Sunday to reclaim his No. 1 spot in the world rankings.

PALM HARBOR, Fla — One great round. One solid swing out of the rough. One clutch birdie putt.

That’s what Luke Donald needed to win the Transitions Championship in a playoff and get back to No. 1 in the world.

Donald was starting to feel overlooked in the two weeks since Rory McIlroy replaced him atop the world ranking, and he even allowed a few doubts about his game to creep into his head.

That changed on a steamy Sunday at Innisbrook, where Donald closed with a 5-under 66 and won a four-man playoff on the first extra hole with a 7-iron out of the rough to 6 feet below the cup for birdie to beat Jim Furyk, Robert Garrigus and Bae Sang-Moon.

“I think people ... thought that my last year was maybe a little bit more of a — not a fluke, but I don’t think many people thought I could do that all over again this year,” Donald said. “Hopefully, I can prove them wrong.”

With his fifth win in his last 31 starts around the world, Donald went back to No. 1 and will stay there until he gets to Augusta National and tries to capture his first major championship.

McIlroy wasted no time sending his congratulations through Twitter.

“Well I enjoyed it while it lasted! Congrats (at)LukeDonald! Impressive performance!” he tweeted.

He followed with another tweet that at least he won’t have to change his profile picture, taken late last year with McIlroy flashing a No. 2 sign alongside his girlfriend, tennis star Caroline Wozniacki.

“I’m sure he got a taste of the view and I’m sure he’ll want more of it. He’s a great player,” Donald said. “I think golf is in a good spot right now. There’s a lot of excitement going on.”

The only fluke was how Donald returned to No. 1 — by winning a playoff, just like he did at Wentworth last May when he first rose to the top of the world ranking.

With so many possibilities in this wild final round, only the best golf was going to get rewarded.

Garrigus birdied the last two holes for a 64 and was the first to finish on 13-under 271, which turned out to be enough for the playoff. Bae, the South Korean with the fluid swing, made a 6-foot par putt on the final hole for a 68. Furyk had a 69 and was the last one to join the four-man playoff.

Missing from the group was Ernie Els, whose bogey-bogey finish cost him a chance to win — and maybe a trip to the Masters.