John Millington, a 26-year-old Royal Mail worker from Droylsden just outside Manchester, was ridiculed on the internet after being filmed in floods of tears shortly after Luke Moore scored the only goal of the game at the Liberty Stadium in March.
That defeat saw City relinquish the lead at the top of the Premier League table to rivals Manchester United. Sir Alex Ferguson's side were only one point clear at that stage - but their lead was later stretched to eight points before City start clawing the advantage back.
Now City are in a position where they just need to beat Queens Park Rangers at home on the final day of the season to secure the title.
"I really think (my crying) made the difference," Millington told the Manchester Evening News.
"Even (Roberto) Mancini said they had to win it for me and I think the players realised that.
"United’s players must have seen it too and it seems to have put the pressure on them. I like to think I started the mind games back then and it seems to have done the trick."
Millington, who at the time denied that he was in tears - claiming he was merely frustrated - believes his role was so crucial that City might invite him to take part in any post-title celebrations on Sunday.
"I was talking to one of my mates about it. We were wondering if Mancini would ask me to come on the bus with them or even lift the trophy on the pitch. I’ll wait for his call," he said.
"As for the United fans who gave me a load of grief – well it looks like I’ll have the last laugh. Although, having said that, one Red who made T-shirts with me crying on them has said I can have them for free."
Millington did admit, however, that he is not convinced the job is done yet.
“I have this horrible feeling that QPR will ruin it for us with (ex-Blues) Shaun Wright-Phillips, Nedum Onuoha and Joey Barton in the team.
"One thing is for certain - whatever happens there will be tears again.”
You can see Millington's reaction to Swansea's goal again in the video that should autoplay in the picture box. (UK users only)