Pep Guardiola's side held a 2-1 first leg lead against the Spanish giants in their round 16 clash before coronavirus brought football to a standstill.
Mendy said: “We have an opportunity to go far in this cup and we want it, so everybody wakes up, works out, stays focused on the target for when they say we can come back. We don't have the Champions League yet so it is the dream.
“We had a good game in Madrid and now we still have to play the second leg. I know that in the minds of every player they know that just because we won there does not mean that it is finished or that we are qualified.
“It is not every day that you go to somewhere like the Bernabeu and perform like that in the Champions League."