The Red Devils currently lead their neighbours by three points, however, defeat to Roberto Mancini’s side would see United surrender top spot to City.
Carrick believes the title race will not be over after the derby, even if Sir Alex Ferguson’s side prevail at the Etihad Stadium.
"Whatever happens, the title race won't be over at the final whistle," he told club's official website.
"Obviously we're the two main contenders and this is going to be a big three points, but there will still be two games left to play and the way the last couple of weeks have gone, I don't think you can look at the derby as a decider.
"Who knows what might still happen? We can only look at this game as an opportunity to win three points.
"Don't get me wrong, it would be a massive step towards the title if we win, but it won't hand us the trophy."
The England international has won the league five times in his six years at Old Trafford and believes none of them have been easy, but Carrick is hopeful an excellent run of form at the turn of the year will be enough for United to secure a 20th top flight title.
"We are still in a good position," he said. "We're three points in front with three games to go. I think some people have forgotten that.
"Every time we've won the league since I've been here it's gone right down to the last couple of games.
"We've never won it with loads of games to spare. It just doesn't happen. Throughout the season you drop points and you can drop points at any time.
"We went on an incredible run after Christmas and put ourselves into a good position but we still have a job to do."