Marco Reus
Reus ruled out for a month.Getty

Arsenal have been handed a potentially decisive boost ahead of their Champions League showdown with Borussia Dortmund with news that Marco Reus is set to miss a month of action.

Reus suffered an injury to his left ankle following a challenge from Scotland's Charlie Mulgrew in the dying minutes of Germany's 2-1 win over Gordon Strachan's side in their opening European Championship qualifier on Sunday.

A statement released by Dortmund read: "A scan carried out by BVB's club doctor Markus Braun at Dortmund's Knappschaft Hosptial on Monday revealed that Reus suffered a sprained ankle as well as a partially torn ankle ligament and is expected to be sidelined for four weeks."

The 25-year-old missed Germany's World Cup triumph due to an injury to the same ankle but had made an earlier than expected comeback at the beginning of the Bundesliga campaign against Bayer Leverkusen.

Reus will miss the visit of Arsenal next Tuesday and his side's trip to Anderlecht at the beginning of October. He will also miss five league games for Jurgen Klopp's side, including his side's visit to Schalke on 27 September.

Arsenal could receive a further boost ahead of their trip to the Westfalenstadion next week amid suggestions Mikel Arteta will be fit for the European clash. The Gunners skipper suffered an ankle injury in a play-off against Besiktas three weeks ago but according to the Mirror, he is in contention for Saturday's meeting with Manchester City.

The Gunners are however sweating over the fitness of Mesut Ozil ahead of two crucial fixtures early in the season. The 25-year-old initially suffered the knock during his side's 1-1 draw with Leicester City last Sunday and was subsequently ruled out of Germany's 4-2 defeat to Argentina and Sunday's victory over Scotland.

The extent of Ozil's injury is yet to be confirmed but the German is considered a doubt for the visit of the champions on Saturday afternoon.