FINAL LEADERBOARD:
-16 Johnson (US) -15 Duval (US), Holmes (US) -13 Marino (US) Selected others: -11 Mickelson (US) -9 Harrington (Ire), Donald (GB)

Dustin Johnson birdied the final hole of the Pebble Beach National Pro-Am to pip former world number one David Duval and successfully defend his title.

Johnson carded a final round 74 for a 16-under par total of 270, while Duval shot a 69 to finish joint runner-up with JB Holmes, both one shot behind.

The 25-year-old Johnson becomes the first person to claim back-back titles at Pebble Beach in 20 years.

Ireland's Padraig Harrington finished well down the field, seven shots back.

However, Harrington's joint 16th place has taken him back into an automatic spot in Europe's Ryder Cup standings.

Last year, Johnson's 54-hole lead gave him victory when rain washed out the final round, but this time the American had to work to the bitter end.

He put his approach to the final hole into the front bunker but blasted out to just over three feet and made a birdie putt to become the first player since Mark O'Meara in 1989 and 1990 to win two consecutive titles in this event.

"All you can ask for is a chance to win on the last hole," said Johnson. "It's such a gorgeous hole. If you miss it a little left, it's not so pretty."

Johnson also becomes the first player since Tiger Woods to come out of university and win a tournament in each of his first three years on the PGA Tour.