The defender was rated as a doubt by Arsene Wenger on Thursday, but looks to have passed his late fitness test to join up with the rest of the first-team squad. Mustafi was pictured training with the squad on Friday which points to him being available for the north London derby at the weekend.
The Germany international suffered a hamstring injury while on international duty in October and has missed Arsenal's last eight games across all competitions. Mustafi's return will come as a massive boost as the Gunners get set to embark on what is one of the busiest periods of the season.
Per Mertesacker, Rob Holding, Mohamed Elneny and Francis Coquelin have all been used in central defence during the German's absence, and Wenger is certain to be delighted that he can revert to his preferred back line for the game against an in-form Tottenham side.
Danny Welbeck was the other uncertainty apart from Mustafi and the striker also seemed to have passed his final fitness test as he too was involved in the first-team training session on Friday. The Gunners' forward had returned to training during the international break but remained uncertain for the game against Spurs.
It looks likely that Wenger will start with Alexandre Lacazette in the number nine role especially since Olivier Giroud is missing after picking up a thigh injury while on duty with the French national team earlier this week. Arsenal Under-23 star Eddie Nkethiah was also spotted training with the first-team on Friday and will not be a surprise if the manager offers him a place on the bench for Saturday's game.
The 18-year-old striker has been in fine form for both club and country this season. Nketiah scored both the goals as Arsenal came from behind to win 2-1 against Norwich City in the Carabao Cup in October and in the recent international break he scored five goals in two games for the England U19 side to help boost their European Championship qualifying campaign.