He headed straight down the tunnel, limping as he did so, though did later join his team-mates in the dugout to watch the second half.
Saka was a doubt going into the match after also being forced off against Bournemouth and now has just four days to recover before champions City visit the Emirates on Sunday.
Arteta, though, says the problem was a fresh issue unrelated to the Bournemouth knock and the injury will need to be assessed in the coming days.
Speaking to TNT Sports after the defeat, Arteta shook his head when asked if the injury to Saka was a hangover from the Bournemouth match and replied: ‘It was an action, a backheel, and he felt something in this specific action.
‘It was nothing else. Obviously he wasn’t comfortable to continue.’
Asked if he knows how severe the injury is yet, Arteta added bluntly: ‘No.’
In his post-match press conference he was also asked for specifics on the injury and replied: ‘We don’t know anything more than that. It was big enough for us to remove him.’
On whether he regretted starting the winger, he added: ‘No. There was a knock that he had the other day and he was perfectly fine.
‘It’s an action that can produce that kind of injury. Afterwards it’s too late.’
