The Black Cats head for the DW Stadium on Tuesday night for their second game in three days with injuries and illness having taken a terrible toll on Martin O'Neill's squad.
However, they will do so having bolstered their blossoming confidence with a remarkable victory over City which extended their return to 10 points from a possible 15 since the Irishman replaced Steve Bruce at the helm.
But having pulled out all the stops to snatch three priceless points at the death on Sunday, Larsson admits it would be a major disappointment not to build upon that at lowly Wigan.
The 26-year-old Swede said: "Of course it would be, but at the same time, it's going to be an extremely tough game, especially after Sunday.
"It feels like the game is only a couple of hours away, so it is going to be tough.
"But (on Sunday) we did what we had to do and put in a good performance and got the three points, and that's what you need to do.
"Now we want to try to win that game as well. We have put some points on the board and we can relax a bit more and try to play with a bit more freedom."
Sunderland will travel to the north-west with O'Neill's resources having been severely depleted by sickness and fitness concerns, a fact which made their victory over City all the more creditable.
Larsson himself spent New year's Eve in bed with a bug which floored Keiren Westwood and Kieran Richardson, while the groin problem which forced Wes Brown off after just 26 minutes added his name to a list which already included Phil Bardsley, Titus Bramble and Michael Turner.
The former Birmingham midfielder said: "To be honest, it's a bit of a crazy schedule, especially with them [Wigan] having one day extra rest. It doesn't really make sense.
"But I suppose that made the result even more important because it took so much out of us.
"Most of the lads were on their knees in there and really tired and if we had lost the game right at the death, it would have been extremely tough to get yourself going again.
"But now we have got three points on the board and hopefully a bit of confidence, and we can go to Wigan with a little bit less pressure on our shoulders."
In the absence of so many players, O'Neill asked midfielders Craig Gardner and Jack Colback to play in the full-back positions, and was forced to hand Matt Kilgallon a first senior appearance for the club since May 2010 when Brown's afternoon came to a premature conclusion.
Opposite number Roberto Mancini, whose side entertain Liverpool on Tuesday night, used the depth of his squad as he left the injured Mario Balotelli out of the 18 and used Sergio Aguero and David Silva only as second-half substitutes.
City dominated for long periods, but failed to make the most of the chances they created with Edin Dzeko going close on several occasions and Aguero forcing a fine 59th-minute save from Mignolet before substitute Micah Richards hit the bar a minute from time.
However, having seen Nicklas Bendtner before the break and Stephane Sessegnon after it pass up perhaps the game's two clearest opportunities up until that point, substitute Ji Dong-won struck in the fourth minute of injury time to snatch an unlikely victory.
Larsson said: "We said at half-time we didn't want this game to end up like a few others this season against top teams when we have lost by one goal and people have been saying we have done okay, but we have no points on the board.
"Of course, we would have settled for a point - it was an incredibly tough game - but we had some chances.
"We probably had the best chances in the game even though they had a lot of attempts.
"We had the chance with Nicklas and in the second half, Stephane's chance, and then Ji pops up with the winner right at the death.
"They had a lot of chances as well, but the positive thing about our defending today was we gave Simon [Mignolet] a chance - he made some terrific saves, but we gave him a chance to make the saves by not rushing out too high and giving them the room to slip balls in between."