American Justin Leonard fired a four-under par 67 on Saturday to share the third round lead at the US PGA’S Tampa Bay Championship in Florida.

The 1997 British Open winner hasn’t won a US PGA event since 2008 and stood alongside countryman Kevin Streelman and South African George Coetzee on six-under 207 after three rounds at the $US5.5 million ($A5.32 million) event.

Australian Greg Chalmers and Americans Jim Furyk, Ben Kohles and Tag Ridings are all one shot off the lead at five-under.

Chalmers had a round of two-under while compatriot Adam Scott, who started the day one stroke off the lead, slumped to a tie for 21st at one-under for the tournament after a five-over par round.

England’s Luke Donald and Americans Bryce Molder, Jordan Spieth, Brian Harman and overnight leader Shawn Stefani are at four-under.

Leonard, 40, 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.