Manchester City striker Kelechi Iheanacho admits defeat at Southampton is a major blow.
City will head to the Bernabeu for Wednesday's second leg against the Spanish giants on the back of an emphatic 4-2 defeat at St Mary's.
Striker Iheanacho , the only City player to emerge with credit after scoring twice, said: “This game is not good preparation for us.
“The game didn't give us enough confidence to go on Wednesday.
“But we will put it behind us, focus and train and go to the Bernabeu and hope we qualify.
“So many things went wrong in the game. We lost so many balls and we didn't defend quite well and we lost so we are not happy. We will keep it behind us and come back stronger."
City's Champions League hopes are hanging in the balance after a 0-0 first leg draw at the Etihad.
Iheanacho, 19, said: “It is going to be a big challenge for us but we will keep our heads down and keep working hard to get to the final."