Ian Poulter claimed a share of the lead after shooting a seven-under round of 64 at the PGA's RBC Heritage event.
Poulter had an early tee time at Hilton Head and took a liking to conditions, going blemish-free and finishing with a spring in his step by claiming four birdies after the turn.
The Englishman finished tied for 29th at last week's Charles Schwab Challenge, the tour's first tournament back after the coronavirus shutdown, and will start round two level with American Mark Hubbard.
The 44-year-old, who won the last of his three PGA titles in 2018, had shared his discomforting Covid-19 Test on Twitter on Wednesday, but will be glad he put himself through the process.
"Any time you shoot seven under par around this golf course, it's obviously a pretty solid day," he said.
"It's very important being bogey-free. It's a fiddly, testing, tricky golf course."
He went on to reveal the surprisingly light load he taken on in terms of course practice during the pandemic shutdown, adding: "I played three or four rounds of golf in that spell of three months off, and it was apparent – as soon as I came back to hitting balls – I felt like I was swinging pretty good.
"I'm not one that plays round after round after round after round to feel that I need to be ready to play golf. I was super active, I was busy on social media, I was doing lots of different things around the house."
World number one Rory McIlroy had a slow start, closing one over on 72. The Northern Irishman, who has questioned the wisdom of European players who have declined to travel, hit three bogeys along the way.
"I wasn't particularly comfortable out there," he admitted.
"I played here once before in '09, and I just remember not being that comfortable around here then. It's still sort of the same. I'm just not comfortable and sort of trying to pick lines and really commit to shots. I just wasn't as committed as I need to be around here."
There is a chasing pack of seven sitting one-shot back from Poulter and Hubbard, with Sheffield's Matthew Fitzpatrick alongside Jordan Spieth on five under.
Spieth had a dicey start, including a triple-bogey at 12, but ended with a surge of momentum as he birdied seven times on the front nine.
