Colchester's 10 men held on for a 0-0 draw at Hartlepool to dent the home side's hopes of staving off relegation.
Pools needed to win to close the eight-point gap between the sides at the foot of the table.
But they were unable to find a breakthrough, despite the Us being reduced to ten men after 43 minutes when Jabo Ibehre was red-carded for a lunge on defender Neil Austin.
After James Poole hooked a sixth-minute volley wide, Pools had all the possession without forcing a goal.
They spent the second period camped in the visitors' half, but a massed and organised defensive unit proved impregnable.
The closest John Hughes' side came was after 70 minutes when Poole's dipping 20-yard volley hit the crossbar and, when the ball rebounded substitute Nathan Luscombe sent a diving header wide.
Charlie Wyke latched on to a teasing Evan Horwood cross, but U's keeper Sam Walker saved with his legs and, amid a frantic scramble, defender Bradley Garmston seemed to clear with his hand, but referee Geoff Eltringham waved play on.