Keith Nolan slithered to 42nd in the Fort Smith Classic in Arkansas as former US Amateur champion Colt Knost grabbed his maiden Nationwide Tour victory.
Dallas native and 2007 Walker Cup winner Knost, 22, closed with a five-under par 65 to win by a stroke from Darron Stiles on 12-under par.
But Former Walker Cup and PGA Tour player Nolan went backwards after opening with rounds of 68 and 66.
A third round 72 dropped him to tied 31st and he finished poorly, dropping five shots in the last seven holes for a 75 that left him tied 42nd on one-over par.
Level par for the round with seven to play after following a bogey at the fifth with a birdie at the par-five 11th, Nolan bogeyed the 12th before running up a nasty triple bogey seven at the 14th and another bogey at the 16th.
Knost earned $99,000 to move up to from 44th to seventh on the money list with the top 25 earning their PGA Tour cards at the end of the season.
Nolan banked just $2,268, leaping just three spots to 130th in the rankings with $8,749 from five starts.