Evans GPs' Kai Daryanani claimed his first GB4 victory in race three at Brands Hatch, while seventh place for Tom Mills was enough for the 18-year-old to claim the championship title with three races remaining.
Daryanani started from pole, and made a great start to fend off fellow front row starter Aditya Kulkarni at Paddock Hill Bend.
While the two Indian drivers squabbled for position, there was drama at Druids as Colin Queen and Josh Irfan collided, sending cars scattering in avoidance and holding up champion elect Mills in the process.
That necessitated a safety car, though the two cars were eventually able to untangle, so the race was neutralised for just a single lap with Daryanani leading the pack away. Behind, all eyes were on the championship contenders as Webster battled his way to fourth from eighth on the grid and Mills was up to ninth, enough to secure the title as it stood.
For Daryanani, it was an impressive first victory in car racing, as he progressively edged away from the pack, and took the flag over three seconds clear of Kulkarni, who had a train of cars squabbling behind him.
Webster moved into third on lap six at the expense of Harry Burgoyne, knowing he needed to move forward quickly in order to keep his championship chances alive heading to Donington Park in October.
But when he lost that place thanks to McNeilly's lunge at Paddock Hill Bend on lap 10, his chances were extinguished completely, with Mills now up to seventh after teammate Jack Clifford ran wide at Clark Curve on lap eight. The championship challengers held those positions until the end, ensuring Mills leaves Brands Hatch with a 111 point advantage, with only 105 points available at Donington.
Outside of the championship fight, Fox Motorsport's Sid Smith completed perhaps his best weekend in GB4 with fifth place after joining the squabble for the final podium place, while VRD's Zack Ping was sixth.
Clifford finished 1.6 seconds behind champion teammate Tom Mills, with series debutant Sebastian Murray ninth for Graham Brunton Racing, and Dylan Hotchin completing the top-10.
GB4 Championship, partnered by the BRDC, Brands Hatch race three provisional result:
1. Kai Daryanani, Evans GP, 12 laps
2. Aditya Kulkarni, Fortec Motorsport, +3.257s
3. Liam McNeilly, Fox Motorsport, +3.375s
4. Cooper Webster, Evans GP, +3.740s
5. Sid Smith, Fox Motorsport, +4.365s
6. Zack Ping, VRD, +6.038s
7. Tom Mills, KMR Sport, +6.335s
8. Jack Clifford, KMR Sport, +7.981s
9. Sebastian Murray, Graham Brunton Racing, +12.883s
10. Dylan Hotchin, Dylan Hotchin Racing, +21.875s
11. Thomas Lee, Evans GP, +42.413s
12. Colin Queen, Fortec Motorsport, +1m.15.810s
DNF. Harry Burgoyne, Graham Brunton Racing
DNF. Josh Irfan, Elite Motorsport