Thornton, who suffered an arm injury last week, was back in action at the earliest opportunity and hit the target after just eight seconds.
Eleswhere, Jamie Steer scored twice for Ayr Scottish Eagles, who managed to complete a well-deserved weekend double over Nottingham Panthers. Having beaten them 4-2 in the Benson and Hedges Cup quarter-final first leg on Saturday, they won 6-3 in their home Superleague encounter the following evening.
Kevin Conway grabbed the first and last goals for Basingstoke Bison in their 4-3 home win over Manchester Storm after overtime.
Conway gave Bison the lead after just 54 seconds and then struck the game-winning goal after two minutes and one second of overtime.
Newcastle Cobras are still pointless after two Superleague games. They lost 4-1 away to Sheffield Steelers, for whom Scott Allison scored twice.
Brett Stewart scored for the Cobras whose man-of-the-match, their netminder Wayne Cowley, was in inspired form against his former club.
BENSON & HEDGES CUP Quarter-finals first leg: Ayr 4 Nottingham 2; Newcastle 1 Basingstoke 1; Bracknell 2 Manchester 2.
SUPER LEAGUE: Ayr 6 Nottingham 3; Sheffield 4 Newcastle 1; Basingstoke 4 Manchester 3 (ot); Cardiff 6 Bracknell 3.Reuse content