Erik Compton hit a sublime seven-under-par opening 63 at the Greenbrier Classic golf in West Virginia as he bids to continue a remarkable personal story.
The 30-year-old Florida native is a two-time heart transplant patient having suffered health problems since childhood.
However, he refuses to let illness get the better of him and a seven-under round saw him take a share of the first-round lead alongside fellow American Matt Every.
Bogeys at the second and third did not auger well for Compton but a brilliant turnaround in fortunes saw him enjoy an excellent round, with birdies on the fourth and fifth plus a further seven.
"It was a difficult start," Compton told www.pgatour.com. "You have to have drive it good (here). If you do, you can definitely take advantage."
"I hit some really close shots, a couple of good putts. I guess the round just kind of developed like that."
Every's round, which he began on the 10th, was sparked by an eagle on the par-five 12th and he consolidated with consecutive birdies on the 16th, 17th and 18th.
Compatriots George McNeill, Pat Perez and Jeff Overton were hot on their heels a shot back in a three-way tie for third after 64s.
Zimbabwean Brendon de Jonge was sharing sixth with Charles Howell, Aron Price, Matt Bettencourt and John Rollins following 65s.
Richard S. Johnson of Sweden was the leading European, tied for 11th after a 66, while popular Spaniard Sergio Garcia was two under, alongside England's Greg Owen.
Scotland's Martin Laird was a shot further back, while Englishman Brian Davis had a day to forget - he was four over par after carding a 74.