Last month when City were toppled through a late Cristiano Ronaldo strike at the Bernabeu, Wayne Rooney was among those celebrating.
He incurred the wrath of City fans, by commenting on how much he enjoyed Real Madrid's 3-2 win, and retweeting a photo of Jose Mourinho celebrating, and last night continued along the same theme.
Manchester City drew 1-1 with Borussia Dortmund in their Champions League fixture, sitting on one point in their group compared to United's six points from their opening two games.
As soon as Marco Reus put the visitors ahead last night, a watching Wayne Rooney tweeted in celebration;
Boooooommmmm— Wayne Rooney (@WayneRooney) October 3, 2012
He did have some praise for City, though, his England teammate Joe Hart, who he described as the best goalkeeper in the world.
Have to say joe hart has been incredible. For me best keeper in the world— Wayne Rooney (@WayneRooney) October 3, 2012
But he saved his final comment on last night for the City support, indirectly criticising the club's support by retweeting the following.
Them empty seats are a joke— Paul Smith Jnr (@PaulSmithJnr) October 3, 2012
A valid point? City's attendance last night was 43,607 - Less than their 46,000 average gate in the Premier League so far this season.
Yes the Premier League champions should have a higher attendance for their first Champions League home game of the season, but equally Rooney describing it as a 'joke', directly or not, is not going to go down well.
We don't mean to harp on about Rooney's twitter, there are far more important things in football to discuss publicly, but he is treading a fine line with his 'banter.'
There are very few playing professionals at the top level who take digs at fellow clubs, and there is a danger if Sir Alex Ferguson does not have a word and reign him in he will end up on an FA charge sooner or later.
He may just end up with a fine, but if the episode with him swearing in front of a TV camera showed, the FA would have no problem making an example of him if he crosses the line.
The good news is he balanced it out with his praise of Hart, who really did show last night just what an amazing goalkeeper he is.
Is Twitter all going to end in tears for Rooney?
image: © nasmac