Justin Leonard, the 1997 British Open winner who last won a US PGA event in 2008, fired a four-under par 67 on Saturday to share the 54-hole lead at the Tampa Bay Championship.
The 40-year-old American stood alongside countryman Kevin Streelman and South African George Coetzee on six-under 207 after three rounds at the $5.5 million event.
Americans Jim Furyk, Ben Kohles and Tag Ridings share fourth with Australian Greg Chalmers on 208 with England's Luke Donald and Americans Bryce Molder, Jordan Spieth, Brian Harman and Shawn Stefani on 209.
Leonard, who reached all 13 fairways off the tee, seeks his 13th tour title overall and his first since the 2008 St. Jude Classic.
Streelman, 34, is in his 153rd US PGA event with his career-best finishes being shares of third in 2011 at Puerto Rico and Mexico. He began the round sharing 31st place, seven strokes off the pace, but fired a 65 to move up.
Coetzee, a 26-year-old from Pretoria, is playing his first US PGA event that is not a major tournament or World Golf Championships event.