Tyrrell Hatton held his nerve on a gruelling final day to win the Arnold Palmer Invitational and claim his first PGA Tour title.
The 28-year-old Englishman fired a two-over 74 in the final round at Bay Hill to finish on four-under 284, one ahead of Australian Marc Leishman, with South Korea's Sungjae Im one further back in third place.
The swirling wind and the firm and fast greens once again made the conditions extremely testing, with Rory McIlroy among those to suffer as a four-over 76 saw him drop out of contention before finishing tied for fifth on level par.
Hatton, who has four European Tour victories to his name, had a two-shot lead overnight but that was halved after he bogeyed the first after he found sand off the tee and another bogey followed when he took three to get down from a greenside bunker at the fifth.
A superb tee shot to three feet at the par-three seventh steadied the ship and an excellent approach at the eighth set up another birdie which took him back to six under and clear.
Hatton suffered a setback at the 11th when he drove into the lake down the left and further problems at the back of the green saw him make a double-bogey, with his frustration clearly showing as he chastised himself with his putter.
He was briefly joined on four under by Im when last week's Honda Classic winner birdied the 12th, but the South Korean then found water with his second at the 13th as he made a double-bogey.
Hatton's playing partner Leishman, who made a costly double-bogey at the third, kept the pressure on with birdies at the 12th and 16th either side of a bogey at the 14th, but the Englishman refused to buckle over the closing stretch.
Six successive pars, including a messy one at the 16th, took him to the 18th with a one-shot cushion over the Australian and he stood firm once again down the last with a textbook par to secure the victory as Leishman (73) could also only make a par.
Im (73) dropped a further shot at the 15th before birdieing the 16th but he had to settle for third place this week after missing birdie chances at the last two holes.
McIlroy was two behind Hatton overnight but moved into a share of the lead on five under with a birdie at the par-five fourth before the wheels came off for the Northern Irishman.
He did well to escape with only a bogey at the fifth after a wayward second shot to the right of the green, but he was not so lucky at the par-five sixth where he made a double-bogey after going from rough to sand to the rocks on the edge of the lake.
The world No 1 racked up his second double-bogey at the ninth after driving out of bounds down the left and any hopes of a back-nine comeback were scuppered by a three-putt bogey at the par-five 12th.
A birdie at the 16th at least gave him a positive finish to his round and extended his run of top-five finishes to seven.
McIlroy finished alongside Keith Mitchell (71), Joel Dahmen (71) and Danny Lee (75), with Bryson DeChambeau one ahead of them in fourth on one under after four birdies on the back nine, including one at the 18th, earned him a 71.
Matthew Fitzpatrick carded the only sub-70 round of the weekend with a three-under 69 to storm up the leaderboard into a tie for ninth place on one over.
The Englishman birdied four of the first six holes and added another gain at the 16th before making a double-bogey at the par-three 17th where he found the water off the tee.
Danny Willett closed with a 73 to finish joint-18th on four over, with Matt Wallace (75) one further back in joint-24th, while Ian Poulter (74) and Graeme McDowell were among those to tie for 32nd place on six over.
World No 3 Brooks Koepka recovered from his 81 on Saturday - the worst score of his career on the PGA Tour - with a 71 to tie for 47th on nine over.