The U’s started brightly and Anthony Wordsworth and Ian Henderson both went close in the early stages.
The hosts early dominance paid off when they went ahead after 16 minutes through Wordsworth, who confidently swept home a low shot from the edge of the area from Henderson’s pass, after Andy Bond had pounced on Troy Archibald-Henville’s error.
Colchester keeper Ben Williams denied Chris Hackett and then Jake Taylor from point-blank range, as Exeter pushed before half-time. The Grecians started well after the break, with Taylor’s deflected shot sailing inches wide and Williams denying David Noble’s shot with his legs, while Taylor drove just wide.
But Bond doubled Colchester’s lead just after the hour with a fine finish from 15 yards, following Steven Gillespie’s run and pass.
And Exeter’s hopes were dashed two minutes later when Danny Coles fouled Karl Duguid and was sent off for denying a goalscoring opportunity. The struggling Grecians battled gamely after that, but Colchester were worthy winners.