Arsenal manager Mikel Arteta warned Max Dowman he was "not in Disneyland" after the teenage rising star was sent off in the Gunners' shock League Cup defeat by lowly Fleetwood.
The Premier League champions suffered one of the most embarrassing losses in their history when, after the fourth-round tie ended 1-1 in normal time they lost 5-3 on penalties away to fourth-tier Fleetwood on Tuesday.
To make matters worse for the Gunners, Dowman saw red five minutes before the end of normal time.
Although it looked a harsh decision to send off Dowman for aiming a kick towards Harrison Neal, Arteta was unimpressed with the 16-year-old, giving him a stern word as the midfielder trudged off.
Arteta's reaction on the touchline was criticised by some pundits, who felt he should have been more sympathetic towards Dowman, who is now starting an immediate three-game ban for violent conduct after Arsenal lost an appeal against his red card and punishment.
And an unprepentant Arteta defended his response to Dowman's red card in a pre-match press conference on Friday ahead of Arsenal's trip to Liverpool.
"This is the environment, this is the reality," he said. "We are not in Disneyland, we are in the Premier League."
Dowman has been carefully nurtured by Arsenal since making his debut when he was just 15.
"We look after him so much but at the same time we're going to be demanding because he needs to earn the right to play, just like everybody else," said the Spaniard, whose side are level on points with Premier League leaders Manchester City
"The other boys, what are they going to say to me? You need to be fair.
"My reaction comes from a moment of heat and extreme frustration because I know the consequences of that, especially for Max.
"It is not the first time it has happened, it happened another time this month with England (Under-19s).
"And it will continue to happen because of the way he plays and the way he attracts opponents and that's it.
"We have to be able to tell each other what we think because he is 16 and we have to be very protective of him, but at the same time very straight with him about what we expect of him towards the team, individuals and the club."
Arteta, himself a former Arsenal midfielder, insisted all was well in his relationship with Dowman.
"There are no issues. We had a talk yesterday. I have done it. It's not the first time it has happened so we need to put an end to it very, very quickly."