Colchester stifled an in-form Grimsby side to make it back-to-back wins for the first time this season with a 2-1 triumph at Blundell Park.
Goals from Kyreece Lisbie and Micah Mbick turned the game around for the U's after Kieran Green had headed the home side in front early on.
Green Heads Grimsby Ahead
The visitors threatened in the opening minute as Mbick went through on goal, but goalkeeper Christy Pym denied him.