Livingston's top six hopes took a severe dent thanks to a woeful first-half display in Paisley as they fell to a 3-0 loss.
The Lions conceded a penalty barely 20 seconds into the clash with Mark O'Hara slotting home following a ridiculously long VAR check. The visitors never recovered as they found themselves three down at the break.
Luiyi de Lucas - at fault for the first goal - lost his marker to allow Tony Watt to tap home the Buddies' second on 18 minutes before O'Hara casually rolled his second spot-kick into the net just before the break to give Stephen Robinson's men a deserved healthy advantage.
