Welwyn Garden City golfer Tom Lewis saw his challenge for the Valspar Championship disappear after a disappointing second half.
The 30-year-old was tied for sixth at the halfway point at Innisbrook's Copperhead course in Florida, just five shots off the lead, thanks to a bogey-free 65 in round two.
Starting on the back nine, Lewis began with a birdie and added two more at the 14th and 17th before coming home with three more birdies, including sinking a 26-foot putt on the seventh.
But he couldn't find that form over the final two rounds, hitting a three-over-par 74 and a 72, rounds that included 10 bogeys, to slip to 42nd with a tournament total of two under.
Sam Burns took his first win on the PGA Tour winning by three shots from USA compatriot Keegan Bradley.
England's Paul Casey finished with a 68 to jump 26 places to equal 21st on five under, level with fellow Britons Ian Poulter and Russell Knox.
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