Rob Collard and Hugo Cook moved into the British GT3 championship lead after winning a wet-to-dry two-hour race at Donington Park.
The Barwell Motorsport Lamborghini took its second victory of the season as previous points leaders Morgan Tillbrook and Ben Barnicoat retired before the pit stops. Collard and Cook left 15.5 points ahead of team-mates Alex Martin and Jarrod Waberski.
Chris Lulham and Kevin Tse finished second, with Charles Dawson and Aaron Walker third in another 2 Seas Mercedes-AMG.
GT4 produced a maiden win for Paddock Motorsport, Revie Lake and Blake Angliss. Waiting for the mandatory driver-change window rather than stopping earlier for slicks helped their McLaren reach the finish first.
Lake, sixteen, became one of the championship's youngest winners. Daniel Lavery and Darren Turner also settled the GT4 Pro-Am title with their fifth class victory, making Donington significant for both overall and category championship battles.