Stephen Baxter's men took full advantage of other postponments to move top of the Danske Bank Premier League with victory at Ferney Park.
The Mallards frustrated their opponents in the first half but the loss of Ryan O'Reilly at half time, combined with some magic from Jordan Forsythe set the tone for the second half.
Forsythe controlled a clearance on his knee before smashing a volley off the right post to give Crusaders the lead.
An unfortunate Matty Smyth own goal added a second, deflecting Heatley's cross past Brush, and Gavin Whyte could have got his name on the scoresheet only for an excellent interception from Ross Taheny.
Billy Joe Burns added a late third, shooting through a crowded penalty area.
Our next match is at home on Saturday to Immaculata in the Irish Cup.