Adam Hadwin climbed into the lead midway through the Valspar Championship by shooting a seven-under 64 in the second round.
Already in the midst of a career year, Hadwin finished Friday's round with eight birdies and one bogey in Palm Harbor, Florida.
He grouped together five birdies in a row to start the back nine and ended the day at 10 under.
After shooting an opening-round 62, Jim Herman stayed within shouting distance with an even-par 71 to remain at nine under.
South African Tyrone Van Aswegen climbed into third at eight under after firing a six-under 65.
Dominic Bozzelli, Russell Henley and Henrik Stenson are hanging around at seven under.
Stenson is trying to win after withdrawing last week with the flu.
Notables Daniel Berger, United States Presidents Cup captain Steve Stricker, Russell Knox, Bubba Watson and Justin Thomas all missed the cut.
It marked a third missed cut for Thomas since winning twice in Hawaii.
Patrick Reed, who has struggled since the Ryder Cup, made the cut on the mark at even par.