What's the atmosphere like on the streets of Manchester before a derby game?
Irwin: You have a city that will be divided up on the night. That's the way it is. The atmosphere and build-up to this game will be fantastic.
United have been in this position many times before. It's new for City.
No doubt, families and workers (will be divided). There will be a lot of people off work. I can guarantee you that.
Will it be a tense and physical game?
Irwin: It will be tense.
Physical? There's a different kind of physicality in today's game. It'll be quick. It'll probably end up like a game of chess. Tactics will be very important.
I think there will be bigger pressure on City. They have to win, simple as that. A draw will do for Sir Alex Ferguson, so will he adopt a more cautious approach?
Irwin: The midfield is a key area.
United like to control that part of the field and play their measured style.
You always go away from home with a little bit of caution. I don't think United have ever gone into a match looking for a draw, it's not their nature, not their style.
But they know they are up against a team very good at home.
What do you think City have got going for them at the moment?
Parker: They're confident. They're back to where they started this season and that is scoring goals.
It's about how they approach this game: Go all out or be worried about United's big-game experience at this time of the season?
Which players could make a difference?
Irwin: In big games, you look to your goal-scorers so most will be looking at (Wayne) Rooney. But Paul Scholes is a very important player.
He sets the tempo for United. City have got plenty of players as well.
Do you think City will crack under the pressure?
Irwin: (Roberto) Mancini has won titles in Italy.
The assistant manager Brian Kidd has experience in winning titles too. They have many experienced international players. Whether or not they were involved in a game of this magnitude before, in a run-in... it's all about pressure. United have been down this road before.
Parker: They've got big players. But winning things in other countries is completely different from what you have to do to win the Premier League.
It's a different kind of football. It's a difficult situation.
Yes, United players will be nervous too, but they'll handle their nerves better.
United fans will hope that the likes of David Silva and Yaya Toure find it difficult because of the expectations on them to achieve something for the City fans.
This article was first published in The New Paper.