Muscle Milk Pickett Racing continued to lead the way in practice at Road Atlanta, with Klaus Graf topping the time sheets in the second of three sessions Thursday.
The German reeled off a best lap of 1:23.336 in the 60-minute rain-soaked session, edging out the No. 0 DeltaWing coupe of Katherine Legge by nearly five seconds.
Third quickest overall and leading the way in the GT class was the No. 17 Team Falken Tire Porsche 911 GT3 RSR of Wolf Henzler. The Porsche factory driver recorded a 1:30.102 lap time.
Ozz Negri led the way in Prototype Challenge in his 8Star Motorsports Oreca FLM09 while Nicolas Armindo took the sole-remaining NGT Motorsport Porsche to the top in GTC.
No major incidents were reported in the session. Only 18 of the 34 entries recorded times.
A two-hour night practice session is on tap for 7 p.m. EDT.