Brannigan believes his side can spring an upset tonight, despite his side's poor league start.
He told the Oxford Mail: “I truly believe we can nick a win and I'm not just saying that.
“People might laugh at me and say 'but look at the way they've started', but at the end of the day I truly believe this team is good enough to do whatever we want to do.
“I believe in the staff, the lads and everyone at the club. If we can get the win it could change the season round like that."
The Manchester United fan added it is his dream to score against City, and his side will not be unfazed by their Premier League-winning opponents.
“My dream has always been to score against Man City and be on my knees in front of the crowd.
“I'll probably get some stick because I know people who will be in the City end.
“Of course, they're human beings and that's it. People sometimes get ahead of themselves and think 'he's this or that'.
“At the end of the day they're good at a sport, but so are we.
“I truly believe in this team and I'm not just saying that. Everyone's just got to believe and stay with us.
“When it happens everyone will say 'he was right'."