Villa approach the game on the back of a disappointing 4-1 Barclays Premier League defeat to Southampton on Saturday and are still yet to win away from home this season.
But Holland international Vlaar has called for Paul Lambert's men to put the weekend's frustrations behind them and focus on finding some form as quickly as possible, starting in Manchester.
Vlaar told the club's official website: "We have to stay strong now and we have another game which we need to prepare for.
"Of course, it is going to be a difficult game but every game is difficult. We will go and try to win the game.
"We can play well as a team, we know this, but we didn't do it in the second half against Southampton and that's disappointing for everybody - the players, the manager, the coaching staff, and of course, our fans.
"Everybody wants to do better and I hope we can show this in the way we play against Manchester City."
Lambert's side could be weakened as the Villa boss waits to hear news about midfielder Stephen Ireland's suspected broken arm.
The former Manchester City player could miss out on a return to the Etihad Stadium after he came off at half-time on Saturday.
Chris Herd and Fabian Delph are both available after injuries and could feature but it could still be a game too soon for Marc Albrighton (foot), while Richard Dunne (groin) and Gary Gardner (ligaments) are long-term absentees.
Roberto Mancini looks set to make wholesale changes to his City side after Sunday's hard-fought 1-1 draw at home to Arsenal, which followed on from a breathless Champions League clash against Real Madrid at the Bernabeu last Tuesday.
Carlos Tevez and Mario Balotelli are likely to lead the line while youngsters Denis Suarez, Abdul Razak and Luca Scapuzzi will be in the squad.
Villa defender Joe Bennett, who made his debut from the bench in Saturday's defeat at St Mary's, believes the pressure will be off his side in tonight's match.
"We have the character to bounce back from this, definitely," Bennett told AVTV.
"We have the cup game at Manchester City. It's good to get a game so quickly to put things right. We want to learn from what's happened and move on quickly.
"You're going to have ups and downs in football, that's part of the game. We're disappointed now but we plan to move on quickly. We're going to the Etihad and not many people are expecting us to win. That can be a good thing.
"That can help, when you don't have pressure on you. Hopefully we can go there and do a really good job.
"They have a big, strong squad and I think whoever plays will be of high quality. We have to match them and show the travelling fans we can get a result."