Mickelson birdied the 18th to cap a round of 66 Sunday at Muirfield. (Lyons/Getty Images)
Phil Mickelson won his fifth career major and first Open Championship Sunday at Muirfield, matching the low round of the week with a 5-under 66 that included four birdies over his final six holes.
"This is such an accomplishment for me," said Mickelson, who also recorded his lowest career final round in a major. "I never knew if I'd be able to develop the game and the shots to play links golf effectively. To play what is arguably the best round of my career, to putt the way I putted, to shoot the round of my life, it just feels amazing to win the claret jug."
Mickelson was the lone player under par for the week at 3-under 281. Henrik Stenson finished second three strokes back.
The victory gives Mickelson three legs of the career grand slam and is his second in as many weeks after his victory at the Scottish Open last week. He also earns 600 FedExCup points with the win.
Others with five career majors include Byron Nelson, Seve Ballesteros, James Braid, J.H. Taylor, Peter Thomson and now Mickelson.
Prior to this year, Mickelson had just two top 10s in 19 career appearances in the Open with his best finish a runner-up in 2011.
This year he was one better thanks to a spectacular final round.
Mickelson went out in 2 under, making two birdies and no bogeys before a hiccup on the 10th.
Meanwhile, overnight leader Lee Westwood had staked as much a three-stroke lead over the field Sunday only to falter with four bogeys in a nine-hole stretch in the middle of his round.
Westwood finished four shots back in a tie for third after a 75, along with Adam Scott and Ian Poulter, all of whom stumbled at one point or another on Sunday.
The lefthander played his final eight holes in 4 under with no bogeys, beginning with an 8-footer for birdie on the 13th to get back to even par for the week.
One hole later he drained a 20-footer for another birdie before reaching the par-5 17th in two to set up yet another.
On the 18th, his approach landed 10 feet from the hole to set up one last birdie, after which he raised his arms skyward.
Mickelson went off to hug his wife and kids while his caddie broke down in tears.
Six times a runner-up at the U.S. Open -- including this year -- golf's oldest major championship was Mickelson's.
"This is a day I'll remember my entire life," Mickelson said. "It was one of the best rounds of golf I've ever played."