Wigan warmed up for the quarter-final of their FA Cup defence at City on Sunday with a fifth successive win against Nottingham Forest.
Former City favourite Rosler said: "Now I can enjoy myself to go to Manchester City.
"It is the highlight for everyone involved with the club again - even though we are FA Cup holders.
"It always is when you get to the sixth round, we have only done that twice in our history.
"It gives us a chance to measure ourselves against probably the best team in the world at the moment - after Bayern Munich maybe.
"It will be a great day for the supporters, players and for me. I will enjoy myself to go there."
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