Phil Mickelson of the US smiles as he holds the Claret Jug after winning the British Open golf championship at Muirfield in Scotland, July 21, 2013. [Photo/Agencies]

GULLANE, Scotland - Phil Mickelson of the US has won the British Open with a spectacular finish.

Mickelson shot a 5-under 66 Sunday to match the best round of the tournament and win his first claret jug. The celebration began while there were still four groups on the course. Lefty birdied four of the last six holes, capped by a 10-footer at the tough 18th to claim his fifth major title.

As soon as the ball dropped in the cup, Mickelson pumped his fists in triumph, knowing it would be hard for anyone to chase down his 3-under 281 total. He headed off to hug his wife and kids while his caddie broke down in tears.

Lee Westwood started the day with a two-stroke lead but his chances ended when he failed to make eagle at the 17th. Adam Scott briefly held the outright lead on the back side, but four straight bogeys ended his hopes of a second major title.