Livingston boss David Martindale admitted his side’s defending cost them points in Paisley.
The home side netted a dramatic 90th minute winner despite being reduced to 10 men - and having conceded an equaliser to the Lions just four minutes earlier.
An otherwise drab affair suddenly burst into life in the final stages. Keanu Baccus had nodded the Buddies in front midway through the second-half before Jonah Ayunga saw red on 76 minutes for handball after blocking a goalbound Scott Pittman strike.
