In the #911 Porsche, Tandy clocked a 50.065sec lap of the 1.474-mile course in Connecticut to beat Oliver Gavin’s time in the #4 Corvette C7.R by a healthy 0.333sec margin.

Gavin is again sharing with Marcel Fassler this weekend while regular partner Tommy Milner recuperates from his hand injury.

Just a whisker slower than the ’Vette was Connor de Phillippi in the #25 BMW M8, with defending champions Jan Magnussen and Antonio Garcia fourth in the second Corvette.

Richard Westbrook led the way for Ford in the #67 GT ahead of John Edwards (BMW), Dirk Muller (Ford) and Laurens Vanthoor (Porsche).

Mario Farnbacher in the Meyer Shank Racing Acura NSX led the GT Daytona class but outpaced Jeroen Bleekemolen’s Riley Motorsports Mercedes-AMG GT3 by less than 0.1sec.

Bryan Sellers was third fastest in the Lamborghini Huracan of Paul Miller Racing, mere hundredths slower, while Pat Long narrowly edged the Porsche battle for fourth, his Park Place Motorsports entry a sliver faster than Matt Campbell in the returning Wright Motorsports entry.

Second practice begins at 2.20pm local (Eastern) time.

Session results: