American Ben Griffin leads the Procore Championship by three strokes after carding a second-round 66 at the Silverado Resort in Napa, California.
Seamus Power shot up the leaderboard following an impressive second round 69 to move into a share of 26th place ahead of Saturday's third round.
The Waterford man enjoyed a bogey-free Friday and made three birdies on the fifth, 15th and 18th holes to move to four under in total, moving 25 places up the leaderboard following his opening round 71.
Starting on the back nine, 29-year-old Griffin birdied the 12th, 15th 17th and 18th holes to head into the afternoon with a wealth of momentum.
He added two more birdies on the back nine without dropping a shot to improve to 14 under at the halfway mark of the tournament.
Griffin leads by three from US Ryder Cup colleague Russell Henley and amateur Jackson Koivun, who shot up the leaderboard on Friday with a score of six under.
The highlight for Koivun, who helped the US win the Walker Cup a week ago, was a spectacular eagle on the par-five 12th – the 20-year-old finding the hole from 271 yards out on the left fairway.
Overnight leader Mackenzie Hughes fell drastically off the pace after carding a score of two-over 74 to sit equal-seventh on seven-under par.
