PGA rookie David Skinns fired a 63 to claim a share of the lead in the AT&T Byron Nelson in Texas as Seamus Power finished his second round with a flourish.
The Englishman, in his rookie season on the PGA Tour at the age of 40, carded 10 birdies and a solitary bogey to join local favourite Ryan Palmer on 15 under par, Palmer having also recorded 10 birdies in a flawless 62 at TPC Craig Ranch.
The pair are joined in a three-way tie for the lead by Colombia's Sebastian Munoz, who followed up his stellar opening round of 60 with a more sedate 69 on Friday.
Power's round of 67 moved him to a tie for ninth place, just four shots adrift of the leading pair. The Waterford man, who began his round on the 10th, hit four birdies in his final five holes to play himself back into contention.
John Murphy won't take any further part in the tournament. Thursday’s 76 meant he was unlikely to get near enough the cut line of –5, but did sign off with a round of 69 that included five birdies and two dropped shots.
Former Masters champion Charl Schwartzel lies two shots off the pace following a 65, with Jordan Spieth also shooting 65 to reach 12 under as he warms up for his attempt to win next week's US PGA Championship and complete the career grand slam.