Title hopefuls Crusaders were left reeling at Seaview as Glenavon pulled off a 4-1 Irish Premiership victory.
Kevin Braniff netted a close-range opener for the Lurgan side with Declan Caddell getting the Crues level.
Two goals in three minutes at the end of the first half through Eoin Bradley and Braniff put Glenavon 3-1 up.
The Crues' hopes of getting something from the game ended in the 76th minute ended when Ciaran Caldwell punished a mistake by Sean O'Neill.
The Crues keeper had come out of his area to collect a throw by Billy Joe Burns but his attempted pass was intercepted by Caldwell who made it 4-1.
The result sees Glenavon leapfrog Crusaders in the table and Gary Hamilton's men are now just a point behind the three teams tied at the top of the table.
Glenavon assistant manager Paul Millar: "If it had been 1-1 at half-time we would have been happy, but we hit them once and then got another on the break.
"At half-time we asked them to be professional and they were.
"We had not won here since 2003, it was a big result for us."