​Basel star Manuel Akanji is reportedly on the verge of joining ​Bundesliga side Borussia Dortmund.

Swiss outlet ​Blick are reporting that a €21.5m deal has been agreed between the two clubs. And the defender being absent from training on Saturday - albeit officially out with a back problem - does point to a potential transfer.

Manchester United v FC Basel - UEFA Champions League

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Akanji was also said to have been spotted on the airport, presumably heading to Germany from Switzerland.

If the reported deal does go through, Akanji will have to compete with Sokratis, Marc Bartra , Ömer Toprak and Neven Subotic for a place at the back at BVB. He will also be the second most expensive player to be sold from a Swiss club, with Breel Embolo joining ​Schalke 04 for €20m, but with substantial add-ons pinned.

The 22-year-old was also linked with ​Premier League sides ​Liverpool, Southampton, West Ham and Tottenham Hotspur, but it appears that ​Dortmund have won the race for the player, who they will expect to slot into their defence, despite the names mentioned previously providing competition.

Akanji, who began his career as a youngster with FC Wiesendangen before moving to FC Winterthur, joined Basel in 2015. He has been quite impressive throughout his career with the Swiss side, helping them secure consecutive Swiss Super League titles in the past two years.

He has made 25 appearances in all competitions for Basel so far this season, scoring twice and assisting another goal.