Lyle lifted a shot over before finding more success with his next attempt, brushing off the challenge of Hogg to tuck home Morton's consolation strike.
But Jelavic was not to be denied with his next attempt, the striker brushing off the challenge of Mulgrew to latch on to Weiss's quickly taken free-kick and sliding a shot past Forster, the ball rebounding off the right-hand post but spinning back over the line.