Romero, one of 46 players forced to finish his third round on Sunday, mixed five birdies with a bogey on the TPC Louisiana layout and watched from the clubhouse to see if his 13-under total of 275 would withstand a back-nine challenge from Lonard.

A tap-in birdie at the par-four 16th moved Lonard into a share of the lead but the Australian's hopes of a first PGA Tour win in three years slipped away with a bogey at the par-three 17th.

Needing another birdie at the 18th to force a playoff, Lonard settled for par and a final-round 69 left him in second place on 12-under 276.

Romero's previous best PGA Tour finish was a tie for third at the 2007 British Open.

New Zealand's Tim Wilkinson signed for a five-under 67 to finish alone in third on 11-under 277 with British Open champion Padraig Harrington (69) and Americans Woody Austin (71) and Nicholas Thompson (71) one shot further adrift.