Mikel Arteta said it was "an accident waiting to happen" - but just how costly could Arsenal's red card problem be to the Gunners' title hopes?
Just eight games into the new Premier League season and already Arsenal have had three players sent off.
William Saliba was the latest to be shown red after he was dismissed for the first time in his career in Saturday's 2-0 loss to Bournemouth, which ended Arsenal's unbeaten start to the campaign.
It follows red cards for Declan Rice and Leandro Trossard earlier in the campaign and each time Arsenal have gone down to 10 men they have dropped points.