Brian Keogh in California

Padraig Harrington had a topsy-turvy finish to his season as Tiger Woods clinched a four-stroke victory in the Target World Challenge at Sherwood Country Club in California.

The European number one closed with a under par 71, going to the turn in three over par 39 before coming home in 32 to finish in eighth place on five under par.

Tournament host Woods started the day final day in a share of second place with Chris DiMarco, one stroke behind US Open champion Geoff Ogilvy on 10 under par.

But he cuised to an emphatic victory, closing with a six under par 66 to win by four shots from US Open champion Geoff Ogilvy on 16 under par.

The world No 1 has enjoyed a remarkable latter half of the season, winning eight times and finishing no worse than second in the 11 strokeplay events he played since missing the cut in the US Open at Winged Foot.

Further down the field, Harrington struggled at the start of his final round of the season, three-putting twice in a three over par front nine that featured four bogeys and just one birdie.

But the Dubliner knuckled down on the way home, picking up birdies at the 10th, 13th,14th and 17th to finish on five under par and earn a cheque for $230,000.

"I really struggled with my focus on the front nine," Harrington said. "But I had four birdies and three other good chances on the back nine. It was nice to go out shooting under par."

After three putting the second, Harrington had to work hard to avoid another three-putt at the next, where he raced his 30 foot birdie putt five feet past the hole. And it was a similar story at the tough par-four fourth, where he came up five yards short of the green and had to hole a six footer to save par.

The par-fives had caused Harrington particular problems all week and he did well just to drop one stroke at the 534-yard eighth after a pulling his second shot into the trees and then crashing into another tree with his recovery.

Playing his fourth stroke from the heavy rough, he looked on in horror it dived into a bunker short of the green from where he splashed out to four feet and holed out for a six.

The only bright spot of an otherwise forgettable front nine came at the 449-yard seventh, where he holed a 40 footer for birdie to get back to three-under-par for the tournament.

But the fatigue of playing eight events in a ten-week spell appeared to be catching up with him as he dropped back-to-back strokes at the eighth and ninth to turn in 39, his worst front nine of the week before coming home in 32.