City meet Real Madrid in the second-leg of the round of 16 leading 2-1 on aggregate.
Walker said, “We missed the Premier League trophy, which was a big blow.
"However, it is worth taking off the hat to Liverpool, because they played fantastically throughout the season and earned the championship. I hope that now Man City will be able to do what they did last year and win the Champions League.
"We proved that we can win the championship of England, only the Champions League remains. Both the players and the coach want this. Some of our players are close to ending their careers, for example, David Silva and Fernandinho. They still have not won the Champions League.
"We are indebted to them, and victory in the Champions League is the least we can do for them."