Second-placed Crusaders came from behind to beat Portadown but it will not be enough to prevent leaders Linfield taking the title.
The Crues are six points behind with two matches left and Linfield's goal difference is better by a margin of 24.
Richard Lecky put Portadown into an early lead but Declan Caddell equalised in the 56th minute.
Portadown's Tim Mouncey was sent-off before a Michael Halliday penalty and Jordan Owens header settled it.
Mouncey's dismissal came on 65 minutes when he impeded Owens from behind as he ran towards goal.
From the penalty, Halliday made it 2-1 and soon afterwards Owens headed in from Gareth McKeown's cross.