Australia's Jason Day wins emotional World Cup

World number 18 Day, mourning the loss of eight relatives killed in the Philippines by Typhoon Haiyan, broke clear of the tenacious Bjorn on the par-four 16th with a nerveless clutch putt for par before holding firm in the final holes.

After tapping in the winning putt on the 18th, the 26-year-old raised his arms aloft in triumph and embraced his grieving mother by the green as a huge gallery of home fans roared their approval.

"For her to be out here over the weekend, and even to have my sisters and my nephew to be here as a family, knowing that I can hold them is very special to me," Day told reporters after winning his second PGA Tour title on another breezy, sunny day at the famed sandbelt course.

"The biggest thing right now is to know that I just didn't give up. It would have been the easiest thing for me to just go ahead and pull out of the tournament with what has been going on over the last week -- just to be up there with my mum and support her.

"But I really wanted to come down here and play with Adam (Scott) and really try to win the World Cup and we achieved that which was great."

Day's one-under round of 70 left him with a 10-under total of 274 in the $8 million biennial tournament where players have competed for individual honours after previously being solely a team event.

Collecting a $1.2 million winner's cheque, Day will also share $600,000 with world number two and compatriot Scott after the pair combined to drive their home nation to a runaway 10-stroke win over the United States in the team component.

Denmark and Japan finished joint third, two strokes further adrift.

Having suffered an embarrassing quintuple-bogey in his opening round of 75, U.S. Masters champion Scott finished strongly with a 66 to finish outright third three strokes behind Day.

World number seven Matt Kuchar, who won the last World Cup for the United States with Gary Woodland in China, scratched out an even-par 71 to finish a further stroke adrift in outright fourth.

Overnight leader by a stroke from the seasoned Bjorn, Day had a roller-coaster start with two bogeys and two birdies in his first five holes, but charged clear of his playing partner when he holed an approach on the first bounce for an eagle on the short par-four sixth.

That put him four strokes ahead, but the Australian stumbled badly on the par-four 10th with a double-bogey after hitting into a thick tangle of scrub left of the fairway.

Bjorn pounced to claw back a share of the lead with birdies on 11 and 13, the latter courtesy of a delightful approach shot that settled a foot from the pin.

However, the 42-year-old Dane was left to rue a wayward tee-shot on the tricky par-four 16th that landed in the woods right of the fairway and led to a bogey.

Day also wobbled, pushing his approach into a wide greenside bunker but rallied with a brilliant up-and-down, landing his recovery about seven feet from the pin and draining the tough downhill putt to take a one-stroke lead with two holes to play.

Bjorn's challenge ended decisively with an errant approach on the tricky par-four 18th that led to another bogey, allowing Day the luxury of a pressure-free par-putt to seal his first professional win on home soil.

"Obviously a fraction disappointed," Bjorn said. "But as a whole it's been a great week. It's been a great pleasure to play on this golf course the way it has played this week and I couldn't be happier for Jason winning.

"He has gone through a rough time of late and for him to even be here is a big thing and then to go and win a golf tournament and for them to win the team event as well, that's what you want to see."