Nicki Thiim and Scott Maxwell made perfect starts to British GT's mid-season trip to Donington Park, leading the GT3 and GT4 classes respectively as opening practice kicked off the weekend.
Thiim's #2 TF Sport Aston Martin was at the top of the times at the very beginning and again when the chequered flag flew, but that does not tell the full story of the session.
The Dane set an early benchmark and held the fastest time for the first half-hour, before Phil Keen went quicker in the #72 Barwell Lamborghini he shares with Adam Balon. The current championship leaders looked set to remain in place, only for Thiim to deliver a blistering late effort that sent him three tenths clear of the competition.
Callum Macleod was third quickest in the #6 RAM Racing Mercedes-AMG, with Lamborghini factory ace Dennis Lind (#18 WPI Lamborghini) and reigning British GT champion Jonny Adam (#47 TF Sport Aston Martin) completing the top-five.
While the GT3 lead swapped hands on a number of occasions, the GT4 class was a more stable affair as the Multimatic squad locked out the first two positions with its pair of Ford Mustangs. The #15 machine earned intra-team bragging rights courtesy of Scott Maxwell, with the #19 machine close behind thanks to Billy Johnson. Scott Malvern was third in the #66 Team Parker Racing Mercedes-AMG.
The session enjoyed perfect conditions, with blue skies and sunshine over the Leicestershire circuit throughout the 60-minute run. There was minimal disruption to proceedings, with a single yellow flag briefly slowing the pace as marshals dealt with a stranded car.
Saturday's second free practice session begins at 11:50, with qualifying getting underway at 15.35. Both can be followed live on BritishGT.com/live-timing.