The former Red made his full debut against City back in 1980, before racking up 378 appearances in total for the club over the next decade, and knows what it is like to play in the hotly-contested affairs.
"I'd always back United against City," he told ManUtd.com. "No matter where it is and no matter where we are in the league, I will always say United will beat City.
"I just watch on television really these days but I always make the point of sitting down and watching the games wherever we are. I've thoroughly enjoyed them turning things around this season.
"For different reasons, it just didn't happen last year even if I suppose the way it finished was magnificent for any neutrals to watch really. This season, they've never really looked in any trouble at all.
"To be fair, I don't think United can be caught at all but it would be nice to win against City as well - even better after what happened last season. But there can be no arguments. It's always been a case of what happens over the course of the season and it doesn't matter about individual matches. Nothing has changed on that front this season."
Duxbury, who won 10 caps for England during his career, has also praised several individuals for their contribution to the title charge.
"I think everybody has been so impressed with Robin van Persie," he stated. "He's that one thing that has made the difference and added an extra dimension. But you've still got other players like Ryan Giggs, who is still performing really well, and others chipping in when they need to.