Marco Reus will become Arsenal’s top £51m transfer target if they fail to secure Alexis Sanchez on a long-term deal

ARSENAL are set for a £51million swoop for Borussia Dortmund midfielder Marco Reus if Alexis Sanchez fails to sign a new deal.

The Gunners are becoming increasingly concerned that their star player Sanchez will leave at the end of next season, with a new deal still not agreed.

Arsene Wenger wants to keep Sanchez on board, but the 28-year-old can walk away on a Bosman if he fails to sign, after a long-running contract saga.

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But according to and SunSport contributer , Wenger is ready to approach Dortmund with a big bid if the deal falls through.

Reus has two years left on his current deal with the Bundesliga club and the club are in no rush to cash in on the 27-year-old just yet.

Arsenal have opened negotiations though, reportedly prepared to offer 60million Euros - or £51m - for his services.

A move from the Gunners is unlikely this season, with the club currently second in the Premier League table, eight points behind high-flying Chelsea who are on 55 points.

Reus' popularity among Dortmund fans should not be underestimated though, the club's support voted him on to the cover of this year's Fifa football video game and is their vice captain behind Marcel Schmelzer.

Reus has had a difficult year with injuries though, an ankle problem keeping him out of Germany's glorious 2014 World Cup campaign and Euro 2016 charge before an ankle injury set him back again.

He did not even appear for his club until November and netted twice on his comeback in Dortmund's staggering 8-4 Champions League win over Legia Warsaw, as well as a crucial last-gasp equaliser in their 2-2 draw at the Bernabeu against Real Madrid.