Coleraine fell to their first home Irish Premiership defeat since 15 August as Glenavon grabbed a 2-0 victory at the Showgrounds.
Glenavon took the lead in the 52nd minute when Rhys Marshall's header from a Kyle Neill corner was adjudged to have crossed the line.
The second was an own goal as Andy Hall's free-kick into the box came off the head of Coleraine's Sammy Morrow.
Coleraine skipper Howard Beverland was sent-off for getting two yellow cards.
The second followed another foul by defender Beverland on Joel Cooper on edge of box.
It meant back-to-back defeats for Coleraine who had assistant manager William Murphy sent from the dug-out by referee Raymond Crangle for comments made to the officials.
In the first half, Glenavon's Simon Kelly hit the crossbar with a firm header.
After Glenavon went into the lead, Coleraine went close to equalising when Rodney Brown's shot across the face of goal was just wide.