Blues boss Hughes watched with interest as Sir Alex Ferguson's side stunned Arsenal with a 3-1 second-leg win at the Emirates Stadium that booked the holders a trip to Rome on May 27 against Barcelona or Chelsea.
The City boss was looking for clues to the likely Reds line-up, but says whatever side his team come up against will make it tough - but not impossible for his in-form side to take three points from.
Hughes said: "Irrespective of who we are up against on the pitch on Sunday, it's about us being positive, and we're going there in good heart and with confidence. We've won our last four games and you have to go to Old Trafford in the belief you can get something out of it. We are in good shape.
"I was looking with interest in regard to who wasn't playing as much as who was, and you look at the bench and who they're bringing on, they've still got great quality they can call upon.
"Sir Alex seems to have the knack of being able to get the rotation correct and the performances don't seem to suffer when he makes those changes in personnel - and that's because of the quality he has available to him.
"It's a big game we need to get something out of. If we pick up points from our last three matches we'll go close."
Pablo Zabaleta and Shaun Wright-Phillips, who was kicked black and blue in the home derby last year, should be available on Sunday.