Viktor Hovland turned the impossible possible on Sunday, overcoming a six-stroke deficit to win the Hero World Challenge.

Collin Morikawa was five shots clear at the start of the final round as the American closed in on the world number one ranking, but Hovland had other ideas in the Bahamas.

On a chaotic day, Hovland – in his first start since claiming the World Wide Technology Championship at Mayakoba – rallied to a stunning one-shot victory with consecutive eagles and a birdie from the 14th and 16th holes.

Despite bogeying his last two holes, Hovland signed for a 66 and the winners' cheque at 18 under, ahead of Scottie Scheffler (66) in front of tournament host and 15-time major champion Tiger Woods as Morikawa capitulated in a final-round 76.

"I didn't think a win was going to be very possible," said the 24-year-old Norwegian star Hovland. "But I know this course is tricky.

"You can make birdies, but it's easy to make bogeys and doubles. If I put a good score up there, you never know what's going to happen."

An unofficial PGA Tour event, Hovland insisted the win felt like an official one given the star-studded field.

"Hell, yeah! There's only 20 guys in the field, but the players here are really good, and I feel like my wins have come when the field hasn't been as strong, so for me to do well in a field like this gives me a lot of confidence," he added.

Morikawa appeared poised to add another piece of silverware to his collection in pursuit of golf's top ranking, but the reigning Open Championship winner crumbled, missing three birdie chances from 10 feet or closer to start the round.

Two triple-bogeys and a bogey capped a forgettable front nine for Morikawa, who dropped another shot at his final hole to end the event tied for fifth – four shots adrift of Hovland, alongside Justin Thomas (64).

Sam Burns shot a three-under-par 69 to earn a share of third spot with former Masters champion Patrick Reed (69).

A four-time major winner, Brooks Koepka had to settle for a slice of ninth position at Albany Golf Club following his two-over-par 74.

Bryson DeChambeau – beaten by rival Koepka in their exhibition showdown in Las Vegas – closed with consecutive rounds in the 70s after going two over on the fourth day.

Former world number one Rory McIlroy (75) ended the tournament 12 shots back, while Jordan Spieth's nightmare Hero World Challenge resulted in a six-over-par display after shooting a 76.