Ireland's Seamus Power carded another three-under 69 to maintain a steady pace heading into round three at the Barbasol Championship.
The Waterford man sits eight shots off the lead after a second round which included five birdies and two bogeys.
Jim Herman established a one-shot lead over fellow American Bill Haas at the top of the leaderboard as players battled searing heat and humidity in Kentucky on Friday.
Herman, winner of one PGA Tour event, vaulted to the front with a seven-under-par 65 at Keene Trace in Nicholasville.
He posted a 14-under 130 halfway total, while Haas shot 66 to move into second place.
The 52-year-old David Toms, who won the 2001 PGA Championship and also played on three American Ryder Cup teams, turned back the clock to shoot a 64 and joined a group of four players two shots behind Herman.
Hank Lebioda, who posted a quadruple-bogey at the first hole on Thursday, shot 64 on Friday and was on 10-under in a tie for 11th.
John Daly, who chose to play in Kentucky rather than the British Open after being denied use of a cart at Royal Portrush, missed the cut.
