Charlie Beljan shook off an uncomfortable night in hospital, firing a one-under par 71 on Saturday to stay atop the leaderboard in $4.7 million US PGA event at Walt Disney World resort.
Beljan defied a doctor's recommendation, returning to the course a day after an apparent panic attack had left him short of breath and caused his blood pressure to spike.
"I honestly didn't think I was going to get through it. I just stayed strong," said Beljan, who even told his caddie on Friday that he feared his life was in jeopardy.
Beljan said he didn't know until Saturday morning that he'd be able to play.
"They released me this morning ... saying that they thought I was good enough maybe not to go play golf, but at least to leave the hospital," he said prior to his round.
"I'm making the decision to come out here and play. Who knows if we'll last two holes?"
Beljan said he began to feel his symptoms return as he approached the turn on Saturday. He had a sandwich, tried to keep calm, and emerged with a round good enough for a 13-under total of 203 and a two-shot lead over South Korean Charlie Wi, Josh Teater and Brian Gay.
Wi carded a two-under 70, while Gay and Teater both signed for 67s on the Disney resort's Magnolia Course.
Beljan entered the tournament at 139th on the money list, with the top 125 at the end of the week due to retain full playing privileges on the US tour next season.
If he can pull off his first career victory, it would guarantee his tour card for the next two years.
Perhaps not surprisingly after his night in hospital, Beljan got off to a slow start with two bogeys in his first three holes.
He rebounded with four birdies before his only other bogey of the day, at the par-three 12th.
"It's nice to be able to walk around and smile," Beljan said. "Yesterday, I was hanging on for my life."
Beljan will still have plenty of work to do on Sunday, with 10 players within three shots.
A group of seven players on 206 included Sweden's Daniel Chopra, who shot 70 and Colombian Camilo Villegas, who also posted a 70.
Villegas came into the tournament ranked 150th on the money list and in danger of losing his card.