Joe Hart has not quite been at his commanding best, but would Manuel Pellegrini drop him?
He failed to punch away a corner, allowing Frazier Campbell to nip in and put the Welsh side into a lead they never let go of.
That, together with a mistake that allowed Scotland to go ahead against England at Wembley earlier in the month, has raised a few questions over the form of the 26-year-old.
Hart has been City's No. 1 since Roberto Mancini opted for him over Shay Given at the start of the 2010-11 season, but could Manuel Pellegrini look elsewhere? Or does he stick with the Shrewsbury-born stopper? Here are a few options the City boss may be mulling over.
The lanky Romanian, who measures up at 6'8", has let no one down when given his chances for City so far.
The 26-year-old was Mancini's choice throughout the FA Cup run last season until the final, when he reverted to Hart.
Pantilimon has yet to start a Premier League fixture for the Blues in the two years since he joined the club. With margins as tight as two coats of paint at the top end of the table, it would be a huge call by Pellegrini to go with Hart's understudy, and one he is unlikely to make.
Former City coach David Platt has reportedly stirred the pot by claiming that the club were thinking of making a bid for Stoke City's Asmir Begovic.
The Daily Mail has picked up on Platt's alleged words on Al Jazeera, and of course it all came to nothing when Roberto Mancini, together with Platt, was sacked before any moves could be made.
Begovic is one of the most underrated practitioners of his art in the top flight, and Stoke would only ever part with him for top whack. It's an interesting story, and is one prompted by Hart's recent form, but is very unlikely to come to anything.
The 32-year-old is not an automatic choice for Real, and according to the Daily Mail last week, Arsene Wenger was pondering a "dramatic" move for the Spain international.
As Alex points out in his Bleacher Report piece, it is unlikely that Hart and Casillas would vie for one place at City, but strange things can happen in transfer windows.
The Brazil international is seemingly out of the door at QPR, who are keen to get the 32-year-old off their wage bill having dropped out of the Premier League.
The R's could have been relegated a lot sooner had it not been for some fine performances from Cesar, but could he also be a potential rival for Hart in City's nets?
Probably not. There's a World Cup looming in his homeland in less than a year, so Cesar will want more of a guarantee of regular football than rivalling a classy performer like Hart.
Last week the Daily Star had him on his way to Benfica, and while it's not happened at the time of writing it looks like he won't be staying in England.
The more likely option is that Pellegrini sticks with Joe Hart.
Yes, he's had his wobbles of late, but while form is temporary, class is permanent, and Hart has this in abundance.
There is undoubtedly hard work to be done in training and in matches, but I'm backing Hart to to get back to his best soon. The nature of his trade means that keepers' mistakes are exposed to the full glare of the spotlight, but Hart is young at 26 and still learning despite his years at the top level.
He'll be happier when he has Vincent Kompany back from injury, and while he may be rested for Pantilimon in the Capital One Cup and FA Cup, don't expect to see Hart out of the City side any time soon.