Pep Guardiola was trying to gain a minor advantage moments before his angry exchange with Bruno Fernandes, in Manchester United's derby victory over Man City.
The Citizens manager was seen arguing with the Red Devils midfielder in the final five minutes of the derby, which United were winning 1-0, at Old Trafford on Sunday.
Fernandes ended the brief exchange by putting his finger to his lips to silence Guardiola, before play resumed and he returned to the action.
The Portugal international was later subbed off by Ole Gunnar Solskjaer before Scott McTominay netted United's second to secure all three points.
Replays showed that moments before the verbal exchange, the ball had rolled off the pitch for a United throw-in.
Fernandes approached Guardiola in a bid to retrieve the ball, only for the Man City boss to throw it straight past him to Luke Shaw.
The left-back would go on to take the throw, but did so from the position the ball landed - not from where it went out of play.
It seems it was this, coupled with the fact Guardiola went to give Fernandes the ball before throwing it past him, that sparked the row.
Red Devils manager Solskjaer was asked for his thoughts on Fernandes 'shushing' his opposite number after the derby.
He said: "You need a character here, you need character at this club, but this team they have got that.
"They have learned through some hard times this season, because we have been a young team and we have started something we believe in and Bruno has helped that."
