Much-changed Birmingham squeezed through to the Carabao Cup second round after debutant Marcel Oakley's late goal downed a spirited Colchester 1-0 at St Andrew's.
Oakley's deflected shot in the 76th minute finally saw off the League Two side as crowds returned to St. Andrew's for the first time since March 7, 2020.
But there was little to cheer for the home fans – whose side showed 11 changes from Saturday's 1-0 win at Sheffield United – before 18-year-old right back Oakley struck.
Colchester created chances through Sylvester Jasper, who ran through only to poke the ball wide with goalkeeper Connal Trueman to beat.
Jasper's curling free kick from out wide then hit the stanchion behind the goal.
Nineteen-year-old forward Jasper, making his full debut on loan from Fulham, let fly with a low angled shot but it sailed wide.
Oakley's strike came out of the blue. The teenager cut inside onto a pass before rifling a fierce shot into the far corner of the net off Tom Eastman.
Substitute Riley McGree's shot on the turn had goalkeeper Shamal George scrambling wide then captain George Friend crashed a towering header wide for Blues.
Cameron Coxe side-footed against the bar and Charlie Lakin cleared off the line as Colchester threatened in time added on.
