Bottom club Airdrieonians and second-placed Partick Thistle drew 1-1 in the William Hill Championship on Friday night.
Euan Henderson gave the Diamonds the lead with 20 minutes left at the Albert Bartlett Stadium but Oisin Smyth equalised deep into stoppage time.
Leaders St Johnstone will have the chance to move five points clear at the top when they face Dunfermline Athletic at East End Park on Saturday.