Arsenal failed to move within a point of qualification to the Europa League knockout phase after a 1-1 draw at Vitoria Guimaraes.
The two sides met on the Wednesday rather than the usual Thursday slot reserved for the Europa League because it clashed with Braga's home match against Besiktas -- and had an early kick off so as not to coincide with the Champions League games.
Unai Emery rested several of his first team stars and it resulted in a sluggish first half with few chances as both sets of players struggled to make an impact.
On 80 minutes, Mustafi expertly headed in Nicolas Pepe's free-kick and it looked like Arsenal would see the game out to make it four wins out of four in the competition.
However, following a melee in the box, Duarte equalised with an impressive bicycle kick.