The 22-year-old ended an 11-year stint with United when he joined the Black Cats in the summer.
Campbell is confident they are capable of beating United.
“It will be a strange one going back and not being a United player, but you know after a while that the time is right for a change of scene,” he told the Sunderland Echo.
“I’m a Sunderland player now and will be giving my best for the team.
“It’s obviously going to be very hard for us – United are still the team to beat in England and Europe.
“But we have been scoring quite a few goals of late and hopefully we can continue that and cause an upset.”
He added: “I was with United since I was 10 – more than half my life, which is a lot when you think of it like that.
“It was a great education. I learned such a lot from being around top players, coaches and obviously Sir Alex Ferguson, who was always around the training ground with advice for younger players.
“Being at United was great, but I asked myself if I was going to play enough games to be the professional that I want to be. The answer was ‘no’ so I had to move on.”