Eriksson told City's website: "We will play the best possible team, maybe after Saturday we should change all of them, but of course you don't do that you give them another chance.
"The important thing is that we as a collective change the mental approach to the game because we didn't have that right on Saturday.
"We have had some of these games in the past as well and we are disappointed.
"Of course Birmingham are a good football team but if you don't have the attitude you won't have even a chance to try and win the game.
"I understand the difficulties when you go to say Bolton because every team will struggle there with the way they play football.
"But I don't think Birmingham were aggressive - they didn't even kick us on the legs! That's why it's disappointing, we should handle matches like that in totally another way than we did."