Asked about his team's lack of fight against Southampton, Mancini said: "I am sure we will change that because I will change players next week.
"I only want players who are ready for the fight in the last 12 games. I am very angry with a lot of my players and very disappointed at the performance.
"It is impossible to play the way we did. We didn't fight for every ball. You need to against an opponent who also wants to win.
"Every team that plays against us plays like it's the Champions League final - this is normal."