Alex McLeish has told his Birmingham players it is time they learnt from their defensive mistakes.
Blues left Gabriel Agbonlahor wide open to head a late winner in the recent second-city derby at St Andrews.
And City then paid the penalty from two set-pieces as Bolton condemned them to a 2-1 home defeat last weekend.
Birmingham visit fellow-promoted side Burnley on Saturday and McLeish knows any more defensive faults could cost them dear this season.
"I have spoken to them and they have simply got to learn from the naive moments that we've had since the beginning of the season," he said.
"We have made a solid start with seven points from seven games. If we continue that progress, we will be there or thereabouts in terms of retaining our Premier League status.
"I don't think there is any doubt about that. We've not looked out of place against any team so far in the Premier League.
"But it is a learning process for some of them. They certainly believe in themselves but they will find the little, minor details are the difference between the Championship and the Premier League.
"You have to learn some hard lessons. I did it myself when I was a young player. I studied my mistakes and said I'll do things differently next time.
"That's what the Roger Johnsons and Scott Danns in the current side have got to do."
Johnson and Dann have made their top-flight debuts this season after arriving from Cardiff and Coventry, respectively, in the summer.
Both started last weekend's setback against Bolton but McLeish has the option to make changes with the likes of Franck Queudrue and Liam Ridgewell available again after injury.
"In terms of defensive options, it is a lot healthier," said the Blues boss.
"We have got a strong squad from which to select so it gives me a selection headache.
"But I would rather have that than having to shift players into unfamiliar positions. The next thing will be players frustrated at not playing.
"That's up to the players in possession of the jersey. If the guys in possession are doing well, the other fellows don't have a grievance."
Full-back Stuart Parnaby and forward James McFadden could also be fit to return to action at Turf Moor, while striker Cameron Jerome (ankle) is on course to be back in contention after the international break in two weeks.