Mancini last night hinted he will let Johnson go only if he gets players in before the transfer window shuts.
He said: "We will have time to talk about this after we play Southampton but it's difficult for us because we need to have players. When we start Champions League games we play every three days for 10 months.
"Adam is a player that deserves to play because he is a good player - but sometimes it's not easy because I can only play 11 players. I understand his position. Every player that can't play is frustrated."