Arsenal will give late fitness tests to Alexis Sanchez and Laurent Koscielny in order to determine their availability for the resumption of the Premier League season at Watford. While Sanchez is yet to return from the climax of Chile's failed bid to qualify for the World Cup, Koscielny missed the international break with an Achilles injury and is unlikely to figure.

The Gunners' injury problems were accentuated during the international fortnight after Sead Kolasinac picked up a hip injury in Bosnia and Herzegovina's win over Estonia. Shkodran Mustafi became the first new addition to the treatment table after picking up a thigh problem while playing for Germany, a setback that is expected to keep him out for six weeks.

But Danny Welbeck and Mesut Ozil have returned to training after not playing for England or Germany respectively during the recent break. Welbeck has been out since the draw with Chelsea with a groin problem while a knee issue has dogged Ozil – but the pair are set to return at Vicarage Road.

"I haven't everyone because some are back today, some tomorrow like Alexis," said Wenger. "Kolasinac has a hip problem, we lost Mustafi for 4-6 weeks. I have concern. I will decide tomorrow what I will do. Koscielny has a final test tomorrow, at the moment he is not available. He trained on his own and the signs are positive so he has a test tomorrow."

"I will have to speak to him," the Arsenal boss added on Sanchez, who was part of the Chile side that lost 3-0 to Brazil, ending their hopes of World Cup qualification. "I am more concerned that yesterday afternoon I watched the whole game Brazil against Chile to see how difficult was the game and I must say he got some special treatment in this game. It was a very physical game. Mentally I will have to assess the situation when he comes back tomorrow."

If either of Sanchez or Koscielny are ruled out they will join an injury list that already includes Francis Coquelin, who has a hamstring strain, Callum Chambers who is suffering from a hip problem and Santi Cazorla. The Spanish playmaker is not expected to play again until Christmas after a year out of action.

Laurent Koscielny and Alexis Sanchez
Arsenal are sweating over the fitness of Koscielny and Sanchez. Getty Images