Cameron Champ recorded a career-best nine-hole score of eight-under 28 to surge into second place after round two of the Rocket Mortgage Classic.
The 24-year-old carded five straight birdies through holes two to six and capped off the outstanding run at the Detroit Golf Club with an eagle on the par-five seventh.
FULL LEADERBOARD
The American's momentum simmered on the back nine, where he combined six pars with two bogeys and a birdie for an inward one-over 37.
The mixed bag saw him sign for a seven-under 65 and sit one shot adrift of leader Nate Lashley.
Fellow countryman Lashley maintained his grip at the top of the leaderboard, following up his career-best 63 on day one with a second-round 67.
Starting on the back nine, he carded three birdies and a bogey but remained blemish-free after the turn to overtake Champ and finish on 14 under overall.
Charles Howell III is two shots back, while JT Poston and Ryan Armour are tied in fourth a stroke further back.
Newly crowned US Open champion Gary Woodland missed the cut by three strokes after a second-round 69.
As did Waterford's Seamus Power, who wound up near the foot of the field with a disappointing second round of 77 leaving him at six over par overall after two days.
