Madrid travel to the Etihad Stadium for the second leg of their Champions League last-16 tie against City on Friday, having lost the opener 2-1 prior to the coronavirus-enforced break.
Gabriel Jesus and Kevin De Bruyne condemned Madrid – who had Ramos sent off in the Spanish capital – to defeat at the Santiago Bernabeu in February.
With Ramos sidelined, regular centre-back partner Varane said: "I think Sergio is a very important player for us, but we know that we are a group where we all have our role.
"For example, I always help my team-mates, it is my way of playing and I like to cover others. In the locker room I talk a lot with my team-mates about the tactic, that will never change.
"To win the Champions League we have to be a strong group, with many leaders, we know the importance of Sergio, but we all have to play a great game to qualify."
Madrid head into the second leg having dethroned bitter rivals Barcelona as LaLiga champions after the 2019-20 season was halted in March due to COVID-19.
Zinedine Zidane's Madrid are riding an 11-game unbeaten streak since losing to Real Betis in March.
"I think we are doing well, we have made a very good streak to win LaLiga, we are all doing very well physically," France international Varane added.
"It has been a different preparation and a little strange, comparing it with what we are used to. We have had many days to prepare this final, we have done it as always with a lot of concentration, working on all aspects of our game trying to improve all the time.
"We arrived with confidence for the latest results and with more rest compared to if it had been played in March. I hope we are well prepared to win tomorrow."