Manager John Hughes is hoping it is nothing more than a tweak.
Otherwise, the influential Moroccan faces a month on the sidelines.
"It's that hamstring again," Hughes said in the Edinburgh Evening News.
"We think it is a neurological problem, a wee nerve thing coming from his back, the same as it was the last time.
"We don't think it is a tear or a pull and we have our fingers crossed it isn't, as you'd then be talking about a month out at a time when we have a lot of important games to be played."
Hibernian 8/15, Draw 3/1, Hamilton 11/2