Two goals by Gary Twigg were not enough for Portadown as Declan Caddell scored to earn Crusaders a draw at Seaview.
Crusaders had taken the lead in the 26th minute when Eamonn McAlister blasted past keeper David Miskelly.
Darren Murray nodded on Aaron Traynor's ball for Twigg to fire the Ports level.
Twigg got in behind the Crues defence to put Portadown ahead with 11 minutes left, but Caddell pounced at the near post to turn in Paul Heatley's ball three minutes later.
The big talking point of the match came in the first half, before the goals.
Heatley was brought down on the edge of the box and the ball broke to Crues skipper Colin Coates who shot into the net.
However, referee Mark Courtney had failed to wait to see if there would be any advantage to the home side, and had blown for the foul before the ball hit the net.
It was a decision which annoyed Crusaders and had the ref holding up in hands in a gesture of apology.