The ball landed on the cart path, took two bounces, went into a tree, but rebounded into the clear.

Although in the rough, the 31-year-old Californian, who shot a closing 76 when tied for the lead in the event two years ago, pitched to seven feet and made the birdie putt.

The chasing pack simply had too much ground to make up after that and, with joint overnight leader Mike Weir collapsing to a 78, Oberholser’s level-par 72 gave him the title by a tournament record-equalling five shots from South African Rory Sabbatini.

England’s Luke Donald and Brian Davis had started the final day in third and fourth place, but were already six and seven shots adrift and were unable to climb into contention.

Donald scored a 74 and Davis a 73, leaving them tied for seventh on nine under. Donald had been 10 under after his career-low 62 on Thursday.

Dubliner Paul McGinley finished joint 12th, a closing bogey six for a round of 70 costing him dear.

Leading European was actually Swede Daniel Chopra, who birdied three of the last five for a share of fifth spot.

Weir, runner-up to Phil Mickelson last year, went out of bounds at the long second and bogeyed the next while Oberholser birdied both.

That five-shot difference proved to be the key passage of play, but Oberholser still had to conquer his own nerves and until that fortunate break on the 15th there was a question mark whether he would.

The victory takes him up from 55th to sixth in the American Ryder Cup table - and into the 64-man field for the Accenture World Matchplay in San Diego starting on Wednesday week. He began the week 80th in the rankings.