Travis Wiley was quickest in a mixed-condition second practice session for Porsche Deluxe Carrera Cup North America at Porsche Rennsport Reunion 7.
Wiley reeled off a 1:29.689 in his No. 77 Topp Racing Porsche 911 GT3 Cup car to edge out Will Martin in the No. 9 JDX Racing Porsche by 0.040 seconds.
Sean Varwig was third for Kellymoss, with Ryan Yardley and Jimmy Llibre completing the top-five for Topp Racing and MDK Motorsports, respectively.
Times tumbled in the closing moments as drivers switched from wet weather to Michelin Pilot Sport slick tires on a drying track following morning showers at WeatherTech Raceway Laguna Seca.
Champion-elect Riley Dickinson could only muster the eighth quickest time, behind Alex Sedgwick and Varun Choksey.
The top-ten was completed by series debutant Bayley Hall and Michael McCarthy.
Pro-Am was led by the No. 65 Kellymoss Porsche of Efrin Castro, who recorded the 11th quickest time overall, while Scott Noble edged out MDK teammate Mark Kvamme in the Am class.
Qualifying is set to get underway at 2:20 p.m. PDT (5:20 p.m. EDT), ahead of the pair of 40-minute races on Sunday.
RESULTS: Practice 2