Eric Foss led the way in opening practice for Saturday’s Continental Tire 240 at Watkins Glen International, in a mixed-condition session.
Foss reeled off a quick lap of 1:58.456 in his No. 56 Murillo Racing Mercedes-AMG GT4, outpacing the No. 15 Multimatic Motorsports Ford Mustang GT4 of Scott Maxwell by 0.973 seconds.
The No. 59 Roush Performance/KohR Motorsports Mustang GT4, which features Andy Lally this weekend, was third on the time charts in GS and overall, followed by the No. 33 Winward Racing/HTP Motorsport Mercedes GT4.
Matt Plumb, meanwhile, completed the top five in his No. 76 Compass Racing McLaren 570S GT4.
Only 24 of the 39 entered cars turned laps in the one-hour session, which began in wet conditions before gradually drying out.
The No. 31 Rumcastle LLC Volkswagen Golf GTI TCR of Bryan Ortiz led the way in TCR, while Mat Pombo topped the time charts in ST, in his No. 73 MINI JCW entry.
Two additional practice sessions are on tap for Friday morning, followed by qualifying, which begins at 12:50 p.m. EDT.
RESULTS: Practice 1