Williams was battling alongside Hayden Nissen at the back end of the top 10.
Rookie Chais Tippett was caught in the middle of a three wide battle with the pair, making contact that turned Nissen across into Williams.
Both cars slid off the road at high speed, with Williams making heavy contact with the concrete barrier.
The cars came to a rest in the gravel, prompting a local yellow flag while the race continued to the chequered flag.
Returning series regular Brandon Madden schooled the field, taking the Race 4 victory by 3.3s over Ryan Reynolds.
Madden took the lead at the race start from Reynolds and never looked back, leading lights to flag.
Young gun Matt Basso held on to take third place ahead of Anthony Di Mauro, with Rossi Johnson rounding out the top five.
In a tale of two halves for Riskie Racing, Madden’s win in his category return came alongside a DNF for teammate Scott Andriske after battling towards the front.
Race 3 winner Scott Dornan found himself spun at the hairpin at the mid-point of the race.
Dornan recovered to finish 13th, unable to capitalise on solid speed shown earlier in the weekend.
Reynolds held on to take the round victory after winning both Race 1 and 2, ahead of Madden.
Discussion about this post