The promising Swiss defender was struck down during Saturday's 6-1 defeat to Manchester City.
Manchester City proved a tougher test however, and the Swiss Under-19 international was substituted on 53 minutes after tweaking his hamstring while trying to prevent Sergio Aguero’s third goal.
The defender will have a scan this week to determine the extent of his injury, with a spell on the treatment table now looking likely.
Meanwhile, Steve McClaren has been handed a timely boost by the news that both Dummett and Haidara should return after the international break, rendering Mbabu’s absence less of an issue.
Injuries have plagued Newcastle so far this season with the likes of Jack Colback, Rolando Aarons and Cheick Tiote all being struck down in recent weeks, and an injury pile-up in the last thing McClaren needs with his squad’s confidence fragile as it is.