The Latics head into the rematch of last season's final - which they famously emerged from with a shock 1-0 victory - in fine form, on a five-game winning streak in all competitions.
Their Sky Bet Championship record for February has earned Rosler, appointed in December, the division's manager of the month award and helped them into the play-off places.
Meanwhile, there has been more FA Cup magic for the club, with their defence of the trophy seeing them defeat Barclays Premier League sides Crystal Palace and Cardiff en route to only their third sixth-round appearance in the competition in their history.
With all that behind them - and a continued promotion push in the Championship ahead - Rosler is in no doubt the pressure is off Wigan for this match.
Asked how he had felt when the draw for the quarter-finals had been made, ex-City player Rosler said: "My first reaction was to ban all talk about the game.
"We only started talking this week about it - I think it was important prior to that that we focused on the league.
"And now, off the back of such a good month, I have said to the boys that this is a bonus game.
"Not that we will take it easy, but we will go into it with no pressure whatsoever. The pressure lies on City.
"We have already achieved a wonderful cup run - it is only the third time the club has been in the sixth round in our history, and doing that after last year's win has made it even more special."
City could win a quadruple of trophies this season and they got the ball rolling last weekend by defeating Sunderland 3-1 at Wembley in the Capital One Cup final.
Their next fixture after the Wigan game will see them take on Barcelona away in the second leg of their Champions league last-16 tie, which they will attempt to turn around after losing the first leg 2-0, while they also remain in the hunt for the Premier League title.
Asked if he thought City might not be entirely focused on Sunday's game at the Etihad Stadium given everything else that is on their agenda, Rosler said: "I hope so - that is our biggest chance!
"But I think City have shown this season that they are very consistent.
"They have so much quality, they can win games when they are only on 60, 70, 80 per cent.
"But we have to make sure we try to play our way, and I think the team showed last year - not only in the FA Cup, but also in the league game - that with a certain approach, we can cause City problems."
Last season, their final campaign with Roberto Martinez as manager, Wigan were only beaten 1-0 at City in the Premier League.
But while that and the cup final result may appear encouraging for the Latics, it should also be noted that they were thrashed 5-0 in the Capital One Cup at City in September when Rosler's predecessor Owen Coyle was their boss.