Harold Varner III earned the outright lead at the halfway stage of the Charles Schwab Challenge, where Jordan Spieth impressed and world number one Rory McIlroy catapulted himself into contention.
American golfer Varner carded a four-under-par 66 for a one-stroke advantage following Friday's second round behind closed doors in Texas.
The PGA Tour is back underway without fans at Colonial Country Club amid the coronavirus pandemic, which suspended the season in March.
Varner was joined by Justin Rose atop the leaderboard after Thursday's opening round – the pair producing bogey-free 63s in Fort Worth.
While Rose was unable to keep pace, Varner – seeking his maiden PGA Tour title – used a flawless front nine to remain the player to beat heading into the third round.
Varner holed four consecutive birdies and birdied five of his last six holes after starting the day with a triple-bogey to be 11 under overall.
Former world number one and three-time major champion Spieth and fellow American Bryson DeChambeau (65) are tied for second through 36 holes.
Spieth has struggled for form – his last tournament victory came in 2017. The 26-year-old has posted just 11 top-10 finishes since the start of the 2018 season to drop out of the world's top 50.
But Spieth's revival continued on Friday after back-to-back 65s to be within touching distance of Varner heading into the weekend.
Spieth – who started on the back nine – posted eight birdies, six of those without dropping a shot until the third (double bogey) and fourth (bogey) holes on the front nine.
McIlroy dazzled on the second day, the Northern Irish star firing a stunning seven-under-par 63 to close within two shots of the lead.
The four-time major winner recorded an eagle and six birdies to improve to nine under through 36 holes, alongside Collin Morikawa (67) and Xander Schauffele (66), while Justin Thomas (68) and Rose (69) are a shot further back.
Elsewhere, reigning US PGA Championship holder Brooks Koepka posted consecutive 68s to be tied for 25th and countryman Patrick Reed (69) is a shot behind.
Meanwhile, defending champion Kevin Na (67), Sergio Garcia (70), Jon Rahm (71), Phil Mickelson (71), Marc Leishman (72), Rickie Fowler (69), Jason Day (72) and Dustin Johnson (71) all missed the cut.