The defender missed Newcastle United's friendly against Vitesse Arnhem.
The defender missed the 3-2 pre-season win over Vitesse Arnhem on Saturday after he rolled his ankle in training.
That saw Grant Hanley make his full debut as the Magpies rounded off their pre-season schedule with an undefeated record to their name.
His absence had led to some fears that he would now be missing for the opening game of the Championship season against Fulham on Friday.
But Benitez has moved to allay those by insisting the injury is not a serious one for the Democratic Republic of Congo international.
“He twisted his ankle in the training session. It’s nothing serious but he couldn’t be here [against Vitesse],” he told the Chronicle.
It will be interesting to see if Mbemba will be fit for the opening game against Fulham or if Hanley will be handed a start alongside Jamaal Lascelles.
Benitez has something of a decision to make about his centre back pairing this season, with Lascelles, Mbemba and Hanley all vying for a starting role.
Reports so far have indicated that Lascelles will be first choice in the team moving forward and that the other two are battling to partner him.
If that is the case, it will be intriguing to see which man Benitez opts to go for when both are fully fit.