Linfield suffered a third straight league defeat for the first time since December 2002 as Glenavon won a thriller at Mourneview Park.
Daniel Kearns put Glenavon ahead on seven minutes after combining superbly with Eoin Bradley but Jamie Mulgrew levelled from distance moments later.
A Joel Cooper free-kick restored Glenavon's lead on 53 but Kirk Millar equalised again within two minutes.
Cooper hit the winner on 75 after Andy Hall's free-kick struck the woodwork.
Linfield manager David Healy will probably wonder how his team managed to lose the game.
The Blues appeared to be taking control early in the second half as they dominated possession for a period with Glenavon's former Linfield keeper Jonathan Tuffey having to make a great save to deny Paul Smyth.
But Glenavon then took the lead as Cooper's floated free-kick went all the way to the net after being dummied by Bradley.
Linfield appeared to have regrouped as Millar replied within two minutes but Sean Ward's needless handball on the edge of the own box, then gifted the free-kick which ultimately led to Glenavon's winner.
Cooper had been at fault for Mulgrew's ninth-minute equaliser after he had been dispossessed by the Linfield midfielder but the youngster made up for the error with his two goals.
Recent signing Kearns also produced another hugely impressive display for the Lurgan Blues - highlighted by his early goal - as he showed some fancy footwork and impressive pace.
Linfield manager David Healy:"The pressure doesn't come from supporters or anything else. The pressure comes from me.
"We are not good enough at the minute and it's something that I've got to address. Hopefully in the coming weeks, I will."
Glenavon assistant manager Paul Millar:"Linfield dominated for a spell but what really pleased us was that we didn't give up.
"It was a great game of football from both sides but overall, I thought we deserved the win."