Europa League matches are generally played on Thursday at either 17.55 (BST) or 20.00, however, Arsenals game in Guimares will take place on a Wednesday at 15.50pm.
An Arsenal statement read: As mentioned in previous communications, this match has been switched by Uefa from Thursday to Wednesday due to other matches taking place in close proximity in Portugal.
SC Braga also qualified for this seasons Europa League and their home match against Turkish side Besiktas was also originally scheduled for Thursday 7 November.
Vitorias home ground Estádio D. Afonso Henriques is situated only 15 miles away from the Braga Municipal Stadium and Portugals police force forbids multiple teams in the same region from playing home matches on the same evening.
With FC Porto and Braga both higher-ranked in UEFAs coefficients than Vitoria, it is their games that have been moved.
Incidentally, Vitorias home match against Belgian side Standard Liege has also been re-arranged for the same reason and will take place on Wednesday 27 November.