League Two title-chasing Plymouth were forced to share the spoils with Colchester after the sides drew 0-0 at the Weston Homes Community Stadium.
The Pilgrims are already assured of promotion but were hoping to turn up the heat on League Two leaders Doncaster with a win.
Colchester also have promotion in their sights but lost ground in the play-off race after dropping points in their penultimate home game.
Despite the lack of goals, both sides had chances during an absorbing contest.
Colchester's best effort was a miscued, close-range header from Chris Porter, after a teasing left-wing delivery from Brennan Dickenson.
Porter then screwed another low effort agonisingly wide, this time from Drey Wright's cross.
Plymouth's Antoni Sarcevic got clear down the right after being played in by Graham Carey but his powerful shot flashed wide of the right post.
The Pilgrims went close after a corner from the left appeared to be deflected goalwards by U's defender George Elokobi, before being safely gathered by Sam Walker.