Mahan had gone 169 holes over 11 matches without trailing in this wild tournament until Kuchar won the fourth hole of the championship match with a par, and Mahan never caught up. Kuchar took advantage of a series of miscues to build a 4-up lead at the turn, and then held off a noble challenge by the defending champion.
There was never a dull moment on the back nine. Only two holes were halved, and those were with birdies.
But for all the great shots, the match ended when Mahan went from a tough lie in the bunker to a bush in the desert, and it took him four shots to reach the 17th green. Kuchar wound up winning, 2 and 1, when Mahan removed the stocking cap he used to fight the cold desert air and conceded Kuchar a short birdie putt.
It was the first World Golf Championship title for Kuchar, and it follows a year in which he won The Players Championship. Kuchar became the second player in the last three years to win the Match Play Championship without ever playing the 18th hole.
Mahan was trying to join Tiger Woods as the only back-to-back winners, and he gave it a good shot despite the big deficit halfway through the match.
Day defeated Poulter in the consolation match, 1 up.
It was the first all-American final in five years at the Match Play Championship, and Kuchar's win gave the Americans a clean sweep of the PGA Tour's West Coast Swing for the second straight year. He moves to No. 8 in the world and picked up $1.5 million, and has earned just over $3.2 million from his last two wins.
CHONBURI, Thailand -- South Korea's Inbee Park took advantage of 17-year-old Thai star's Ariya Jutanugarn's closing triple bogey to win the LPGA Thailand by a stroke.
Jutanugarn blew a two-stroke lead on the par-5 18th, driving into an unplayable lie in a bunker, hitting over the green and three-putting for an 8.
Park shot a 5-under 67 to finish at 12 under, and earned $225,000 for her fourth LPGA Tour title. Jutanugarn had a hole-in-one on the par-3 12th and closed with a 72.
PANAMA CLARO CHAMPIONSHIP
PANAMA CITY -- Kevin Foley won the Web.com Tour's season-opening Panama Claro Championship for his first tour title, holing a 15-foot birdie putt on the final hole for a one-stroke victory over Mathew Goggin.
The 25-year-old former Penn State player closed with a 3-under 67 in 93-degree heat to finish at 8-under 272 at Panama Golf Club. He earned $108,000.
Goggin had a bogey, double bogey and triple bogey in his final-round 70. The 2010 champion had a chance to force a playoff with a birdie at the 465-yard 18th, but settled for par after his second shot went into a greenside bunker.
Copyright 2013 by The Associated Press
This story is from ESPN.com's automated news wire. Wire index