Glenavon inflicted a first Premiership defeat of the season on leaders Ballymena with a 2-1 victory.
Kris Lindsay headed in an early opener for the hosts at Mourneview Park before United striker David Cushley squandered four clear chances to level.
Rhys Marshall headed home from a corner to make it 2-0 before Shane McCabe of Glenavon and Ballymena's Allan Jenkins were red-carded on 67 minutes.
Cushley finally found the net five minutes from time but Glenavon held on.
Glenavon made the perfect start with Lindsay glancing in at the nearpost after five minutes from Kyle Neill's corner.
Andy McGrory saw his 20-yard volley land on top of the United net but it was Ballymena, and in particular Cushley, who were the more dangerous in the first half.
The Sky Blues forward volleyed just wide before twice going through clear on goal and both times being denied by keeper Alan Blayney.
Cushley's 12-yard volley flew over and he again only had Blayney to beat just before the break but his close-range chip drifted wide.
Cushley blasted over on the restart and United's frustration grew when the outstanding Blayney raced out to get a vital touch as substitute Darren Boyce sprinted through on goal.
Glenavon were clinical with their rare openings and Marshall nodded in on 65 minutes as United failed to clear from a Neill corner.
Ballymena protested in vain that the corner should not have been awarded while McCabe and Jenkins were shown straight reds after clashing in an off-the-ball incident.
Blayney kept out a fierce strike from Matthew Tipton before Cushley lifted the ball across the keeper and into the net with five minutes left.
Ballymena pressed for a deserved equaliser but Glenavon held firm to secure all three points.
United remain two points clear at the top while the Lurgan Blues move up five places to third.