For City, it provides a chance to atone for their FA Cup Final loss last season. Manuel Pellegrini's side cannot afford to lose their second successive major cup final.
For Sunderland, the cup final provides the opportunity to inject a shot of momentum into a season that otherwise threatens relegation. The Wearside club famously won the FA Cup final in 1973, beating Leeds United in the final at Wembley.
Gus Poyet could do with experiencing similar success come Sunday afternoon.
Let's take a look at the key stories that are likely to feature at Wembley.
Adam Johnson to beat his old club?
Adam Johnson is enjoying a rich vein of form at the Stadium of Light since his move from Manchester City. So much so that the winger is now being tipped to snatch a last-minute place in Roy Hodgson's World Cup squad.
Things were not so rosy for Johnson at Manchester City, though.
The Guardian's Ewan Murray reported last week that he struggled to adapt to life at the City Ground:
Yes, I was disappointed the way it ended. I wanted to go and play more games. I was not asking to play every week – I knew I couldn't – I just asked to play one in four. It was as simple as that. I did not mind playing once every couple of weeks. It just wasn't a fair share.
I was not expecting to play every minute of every game and I always knew that. It was just more the fact that it wasn't getting shared around enough. So I wanted to play somewhere I could play week in, week out and feel more loved.
With a different manager, who knows? I just wanted a little bit more game time. All I wanted was for everyone to be treated the same.
Johnson will seek to show his old club just what he can do, and if Sunderland are to prevail, he must be on form.
Johnson possesses the pace, tricks and delivery needed to be a top-class winger. If he is to fulfil his potential, he must take the game to Manchester City and be prepared to run at their defence.
Joe Hart or Costel Pantilimon?
England's goalkeeper Joe Hart lost his place earlier in the campaign to Costel Pantilimon, but the former Shrewsbury man has now won back his place and established himself as Manchester City's No. 1.
Pantilimon has been a regular for City in the Capital One Cup this season, and to deny the Romanian his moment in the spotlight would be especially cruel given that it would be the second season in a row that he has suffered such a fate.
The Mirror's David McDonnell reported that Pellegrini will not tell the goalkeepers whether they are playing until just before the match.
But Hart says he will be magnanimous if Pantilimon is chosen over him:
You have to be able to accept when you are playing or not. When managers have got decisions to make, whether it benefits me or not, I have to be man enough to take it.
I work hard every day to win and I understand it does not always go my way, and you have to move forward.
Breaking the northeast silverware duck
The northeast of England boasts in Newcastle United and Sunderland two of England's biggest sides. It is all the more surprising, then, that the last time one of those sides took home a trophy was more than 40 years ago, as reported by The Sunderland Chronicle's James Hunter.
Then, second division Sunderland beat Don Revie's legendary Leeds United side 1-0 to lift the FA Cup at Wembley in 1973.
In many ways, Sunday's clash is similar. Sunderland as a distinct underdog, face one of the very best sides in the country. Should they overcome Manchester City, as they did at the Stadium of Light earlier in the season, it will constitute just as great a shock as that legendary FA Cup upset.
The return of Aguero
For a man who has experienced several injuries, Sergio Aguero has enjoyed a profitable season in front of goal. Fifteen goals so far attest to that.
It says much about the rich striking resources accumulated at the City Ground that Aguero is barely missed when injured. But the Argentine returns from five games out with a hamstring injury, and his presence will add to Sunderland's already-pounding headache.