There's nothing Jose Mourinho likes more than getting one over on Arsene Wenger.
It hasn't exactly been plain sailing for Mourinho since his arrival in the summer.
Defeats to Manchester City, Watford, and Chelsea have left United eight points adrift in the title race, and after such a promising start to the season, question marks have surprisingly already been raised over his long-term future in the dugout.
However, Jamie Carragher has pinpointed another moment when the likes of Ed Woodward, Sir Bobby Charlton, and David Gill may have been left questioning whether they made the right appointment.
In his column in the Daily Mail, Carragher recalled Mourinho's rant about Chris Smalling and Luke Shaw after the Swansea game - which United actually won 3-1 - as a possible turning point if things do eventually turn sour.
Both defenders were criticised by their manager for withdrawing from the squad, though it's since been revealed that Smalling has a broken toe.
"I couldn't believe it," Carragher writes.
"I played many games in my career when I felt certain team-mates could have done more, at times, to get themselves on the pitch but my managers never said so publicly.
"This is the Mourinho you expect to see in year three at a club, not month three. These are things that will have worried United fans about him before he arrived.
"It made me wonder what Sir Bobby Charlton, David Gill and Ed Woodward thought on their way home from South Wales.
"Was this the first time they felt some doubts about him? Here was a chance to enjoy two weeks of peace but, instead, his comments fanned flames even higher. That may seem a big thing to say but United are used to doing things a certain way."
Was Mourinho right to call out his own players? Let us know in the comments.