Watson made clutch putts on the final two holes yesterday, including a 12-foot birdie on the par-5 18th for a 5-under-par 67 to win the Farmers Insurance Open in San Diego.

Phil Mickelson — the more popular Lefty and the San Diego favorite — was one shot behind and only 228 yards away in the rough when he decided to lay up before Watson attempted his birdie putt.

Then came a loud cheer as Watson sank his putt for a two-shot lead, meaning Mickelson would have to hole out from 72 yards for eagle to force a playoff. He had his caddie tend the flag — rare for a full shot from the fairway — and the gallery gasped when the ball landed just behind the hole and started to spin back toward the cup.

But it never had a chance.

“I’m disappointed,’’ Mickelson said. “I wanted to start the year off with a win. On the other hand, I played really good golf.’’

Watson finished at 16-under 272 for his second victory, although this one came against a much stronger field than his playoff win at the Travelers Championship in Cromwell, Conn., last summer.

“It showed I can do it,’’ Watson said. “I’ve done it twice now. I’m only 50 behind Phil and about 80 behind Tiger. So they better watch out.’’

Watson held off Mickelson, Dustin Johnson, and Jhonattan Vegas, the rookie from Venezuela coming off a win at the Bob Hope Classic last week. Vegas tied Watson for the lead on the 10th hole and stayed in range throughout the back nine until his 5-iron from the first cut of rough on the 18th came up well short and into the water.

Vegas made bogey for a 68 and tied for third with Johnson, who shot 66.

Tiger Woods also was in the field, although no one noticed during the final two hours. Woods, who started the final round eight shots behind, closed with a 75 to end his five-tournament winning streak at Torrey Pines. He had never finished out of the top 10 at Torrey Pines, but wound up 15 shots back in a tie for 44th.

Champions — Jack Nicklaus and Tom Watson defended their Skins Game title in Kaanapali, Hawaii, finishing with seven skins and $310,000 to edge Mark O’Meara and Bernhard Langer by $10,000.

Nicklaus and Watson took five skins and $250,000 on the par-3 17th. Nicklaus hit a 6-iron from 136 yards to 12 feet and Watson made the birdie putt in the alternate-shot event that they also won in 2007.

O’Meara and Langer had seven skins. Fred Couples and Nick Price claimed $80,000, matching Ben Crenshaw and Fuzzy Zoeller.

European — Paul Casey made a 5-foot par putt on the final hole to win the inaugural Volvo Golf Champions in Riffa, Bahrain, his first victory in 20 months.

Casey needed the putt on The Royal Golf Club’s Montgomerie Course to secure the victory after playing partner Peter Hanson made bogey after hitting into a greenside bunker.

Casey shot 68 for his 11th victory on the European Tour. Hanson (69) and Miguel Angel Jimenez (67) finished a stroke back.