The home side threatened first in a quiet opening to the game on 16 minutes when Fraser Bryden managed to get a cross in from the right.
However, just as a Crusader attacker threatened to get his head on the ball, Harry Murphy managed to clear the ball away to safety before the referee blew for a free-kick in favour of the defender.
On 25 minutes, Glenavon had their first spell of pressure and went close to opening the scoring, but Murphy couldn’t steer home Paul McGovern’s free-kick.
Two minutes after the break Crusaders almost grabbed the lead when Finley Thorndike sent Bryden clear on goal, but the striker couldn’t beat stopper Jacob Carney, who made a superb save.
Then, on 60 minutes, Glenavon broke the deadlock through their first meaningful attack of the half.
Peter Campbell curled a superb delivery from the left and Burns was there to fire home from close range.
Just four minutes later, it was a case of another chance, another goal for the Lurgan Blues.
Once again, it was a Campbell delivery that caused problems for the Crues and Luke McGerrigan leapt highest to powerfully head into the left-hand side of the goal.
On 76 minutes, it was 3-0 when Nathaniel Ferris ran on to a McGerrigan pass down the right and his cross was parried out by Tuffey in goal.
However, his attempted clearance was right into the path of Conor Falls, who had the simplest of touches into the goal to complete an incredible day for the Lurgan Blues.
