GULLANE, Scotland (AP) — Phil Mickelson is mystified no more by links golf. He has his name etched in a silver claret jug to prove it.

Mickelson delivered his best closing round ever in a major yesterday — at the British Open, of all places — when he ran off four birdies over the last six holes for a 5-under 66 at Muirfield to win the third leg of the career Grand Slam.

“This is such an accomplishment for me because I just never knew if I’d be able to develop the game to play links golf effectively,” Mickelson said. “To play the best round arguably of my career, to putt better than I’ve ever putted, to shoot the round of my life … it feels amazing to win the claret jug.”

At the end of a rough-and-tumble week along the Firth of Forth, Mickelson was the only player under par. He wound up with a three-shot win over Henrik Stenson, one of four players atop the leaderboard during a final round that was up for grabs until Mickelson seized control in the final hour.

Lee Westwood, who started Sunday with a two-shot lead, fell behind for the first time all day with a bogey on the 13th and never recovered. He closed with a 75. Masters champion Adam Scott took the lead with a 4-foot birdie on the 11th, and closed as sloppily as he did last year. He made four bogeys starting at the 13th, and a final bogey on the 18th gave him a 72. At least he has a green jacket from the Masters to console him this year.

Tiger Woods, in his best position to win a major since the crisis in his personal life, stumbled badly on his way to a 74 and was never a serious challenger.

Westwood said he didn’t play all that badly. Instead, he paid tribute to what will be remembered as one of the great closing rounds in major championship history.

“When you birdie four of the last six of a round any day, that’s good going,” Westwood said. “With a decent breeze blowing and some tough flags out there, it’s obviously a pretty good experience. When you do it in a major championship, it’s an even better experience.”

But this major championship? Phil Mickelson?

He had only contended twice in two decades at golf’s oldest championship. One week after he won the Scottish Open in a play-off on the links-styled course of Castle Stuart, Mickelson was simply magical on the back nine of a brown, brittle Muirfield course that hasn’t played this tough since 1966.

Tied for the lead, Mickelson smashed a 3-wood onto the green at the par-5 17th to about 25 feet for a two-putt birdie, and finished in style with a 10-foot birdie putt on the 18th to match the lowest score of this championship.

Mickelson figured a par on the 18th would be tough for anyone to catch him. When the ball dropped in the centre of the cup, he raised both arms in the air to celebrate his fifth career major, tying him with the likes of Seve Ballesteros and Byron Nelson.

“Best round I’ve ever seen him play,” said his caddie, Jim “Bones” Mackay. Mickelson shared a long hug with his caddie and whispered in his ear, “I did it.”