Mikel Arteta said Myles Lewis-Skelly must learn from his rashness after escaping a second yellow card in the 7-1 drubbing of PSV Eindhoven.
The 18-year-old was substituted just minutes after committing a reckless challenge on Richard Ledezma in the first half, which arguably should have seen the full back get sent off.
It’s not the first time Lewis-Skelly has flouted the line, following red cards against Wolves and West Ham — though his Wolves dismissal was overturned by the FA on appeal.
Ahead of Arsenal’s Premier League match against Manchester United on Sunday, Arteta said: ‘I think it was quite clear that we had a liability there, with the yellow card and the next action.