Chris Hutchings admitted he was disappointed with the professionalism of his Wigan players following the 3-2 defeat to Birmingham.
Marcus Bent twice put The Latics in front but on each occasion Birmingham were back level within a few minutes, and Steve Bruce's side went on to win the game thanks to a late goal from Olivier Kapo.
Hutchings was disappointed with Wigan's defensive display and urged his side not to make the same mistakes again.
"It was very disappointing to get our noses in front twice and not get anything from the game," he told Sky Sports.
"We didn't hold onto the lead long enough on both occasions.
"The effort was there but the professionalism of making sure they don't score pretty soon after we score wasn't there, so we have to make sure that doesn't happen again."
Luis Valencia was Wigan's standout player on his return from injury and Hutchings was impressed by the Ecuadorian.
"He's a good player and it was great to have him back after being out for six or seven weeks with a knee injury," said the manager.
"It was good for him to get 90 minutes under his belt and the more he plays he'll get stronger and stronger.
"You have to take the positives and we've scored two goals here, but we have to make sure we stay tight when we do go in front."