Tom Hopper scored twice as 10-man Colchester moved out of the relegation places with a spirited 3-2 victory at play-off chasing Crawley.
The visitors went into the game boosted by a bumper following of nearly 1,000 fans, boss Danny Cowley having made a passionate appeal for increased support.
Crawley midfielder Liam Kelly fired against the top of the bar before the Reds went behind after 21 minutes when Ellis Iandolo crossed for Hopper to turn the ball in from close range.
In a dramatic end to the opening half, Crawley equalised after 42 minutes when Klaidi Lolos scored for the third game running.
But Colchester hit back to regain the lead two minutes later, goalkeeper Corey Addai giving the ball away which allowed Jay Mingi to cross for Cameron McGeehan to score into an empty net.
The U’s made it 3-1 a minute after the break as Hopper stroked in his second past the helpless Addai.
Colchester were reduced to 10 men two minutes from time after substitute Samson Tovide, only on the field eight minutes, received a straight red card for an off-the-ball incident.
Harry Forster headed in a cross from Kelly in the seventh minute of added time but Colchester held on for a vital win which lifted them one point above Sutton.