I'd wish the team good luck for Sunday, but I honestly don't believe it's about luck. Sure, you can have a bit of luck now and again but it's balanced out by the odd bit of bad luck now and again. To beat City, Sunderland need an awful lot of luck, OR they raise their game to the best it's been all season and win through hard work, determination and sheer desire.
So, audentis fortunas iuvat? Simple... Fortune favours the brave.
Sunderland make their own good luck. Take the game to the enemy (not too openly), keep focussed, no silly (and costly) mistakes, keep going until 3 seconds after that final whistle. It ain't over till the fat lady sings.
Make the fans happy and proud. It matters not that you win, but it'll feel a whole lot better, not just for the team but for all of Sunderland. Go for it.