The German has fond memories of the competition, some of which are from his spell playing for City in the 1990s, such as scoring four goals in a 5-2 win over Notts County in 1994-95 and being part of a derby tie at Manchester United the following season.
Then, as a manager, he saw his Brentford team draw 2-2 with Chelsea last term, a match in which the League One outfit almost held out for a victory over their Barclays Premier League visitors.
Rosler may well have anticipated there would be more good times to come for him in the FA Cup when he left the Bees for Wigan, the trophy holders, in December.
And so it has proven, with the Sky Bet Championship Latics putting together a run that has included victories over Premier League sides Crystal Palace and Cardiff and will now take Rosler back to City this weekend for what is a repeat of last season's final.
The 45-year-old said: "You will never find a bigger fan of the FA Cup than me.
"As a player, I really enjoyed my FA Cup games - I remember scoring four goals against Notts County, and that was one of my highlights in the competition.
"There was also a game against Manchester United at Old Trafford, where, with the thousands of City supporters there, it was an amazing atmosphere.
"Then, as a manager, last year we had a very good run, with the highlight being when we played Chelsea over two games.
"We were seven minutes away from winning the first game, and it also made a lot of money for Brentford, which we reinvested wisely.
"So there have been a lot of benefits and good memories from the FA Cup."
As part of his preparation for this assignment against Premier League title-chasing City, Rosler has utilised footage of last year's FA Cup final, so famously won by Wigan 1-0, as well as of other games that indicate weaknesses in the Blues.
Those other matches were all eventually won by City, though, and Rosler feels that ultimately, with the size of their task on Sunday, the Latics need to focus on their own attributes more than anything else.
"I gave the players a DVD from (the final) and the league game (at City last season, which Wigan only lost 1-0)," Rosler said.
"We also watched the Watford and Sunderland games. The first halves from Watford and Sunderland was excellent," Rosler said, referring to City's fourth-round FA Cup tie and last weekend's Capital One Cup final. City had to come from behind on both occasions to win.
"So there are opportunities for us, but not a lot, and we have to make sure we make them count. It will be tough, but you never know - we will see what happens.
"I think they know that our team can cause them problems, so I think they will be focused and take it seriously. We have to make sure our main focus is on ourselves.
"If my analysis guy and I tried to cut out all the good things they do, we would be sitting there for two or three hours.
"So I have to make sure we are focusing on us and what we can do, hoping that, on the day, we can be heroes."