SONOMA, Calif. – Veteran Kevin Marshall of Incline Village, Nev., drove the No. 44 VSA Motorsports Lotus GT4 to the fastest time Friday morning at Sonoma Raceway in the opening GTS practice round.

Marshall, the 2009 Lotus Cup champion, jumped to the top of the timing sheets early in the overcast conditions at the 2.38-mile, 12-turn circuit just north of the San Francisco Bay. He battled 16-year-old phenom Nate Stacy of Owasso, Okla.,for the top spot late in the 30-minute practice before securing the quickest time with a one minute, 42.348 second lap at a speed of 83.890 m.p.h.

Stacy, driving the No. 14 Roush Performance Road Racing Ford Boss 302, clocked the second quickest GTS in the first session with a 1:42.703 followed by Utah winner Anthony Mantella of Toronto, Ont., Canada, in the No. 8 Mantella Autosport KTM X-Bow GT4, at 1:43.093, Martin Barkley of Huntsville, Ont., Canada, in the No. 80 Mantella Autosport KTM X-Bow GT4, at 1:43.390 and veteran Jeff Courtney of Milwaukee, Wis., in the No. 99 RecStuff/Kenda/JCR Motorsports Maserati GranTurismo MC Trofeo, at 1:43.758.

GTS class point leader Brett Sandberg of Allendale, N.J., recorded the sixth quickest lap Friday morning at Sonoma with a 1:43.794 in the No. 13 ANZA Motorsports KTM X-Bow.

The next GTS practice round is set for 12:30 pm PDT Friday.