MAINZ, GERMANY - DECEMBER 12: Abdou Diallo of Mainz gestures during the Bundesliga match between 1. FSV Mainz 05 and Borussia Dortmund at Opel Arena on December 12, 2017 in Mainz, Germany. (Photo by TF-Images/TF-Images via Getty Images)

Borussia Dortmund have reportedly agreed a deal to sign Mainz defender Abdou Diallo.

The highly rated defender was also wanted by French club Olympique Lyonnaise, but he has rejected their advances and is now set to join the black and yellows after a long transfer saga. Borussia Dortmund will pay a fee of 30 million euros for Diallo, according to L’equipe. However, BILD say that the fee for Diallo is around 25 million euros. The 22 year old will sign a five year contract with the club once he completes his medical.

Borussia Dortmund were in the market for a centre back to replace Sokratis, who is set to complete his move to Arsenal next month. Now it seems that they have got their man in Diallo, who is one of the most highly rated defenders in Europe.

The former AS Monaco player enjoyed a superb debut campaign in the Bundesliga with 1.FSV Mainz 05 and made quite an impact. He made 30 appearances in all competitions and also scored three goals. Diallo is a centre back by trade, but he can also play at left back. It’ll be interesting to see which role he plays for Lucien Favre’s side.

Diallo is an exciting propect who has the potential to become a top class centre back. And at Borussia Dortmund he can achieve exactly that. Dortmund fans will be hoping that he can improve their defense, which leaked sloppy goals throughout last season.

Once he completes his move, Diallo will become Borussia Dortmund’s fourth summer signing. Marwin Hitz, Marius Wolf and Thomas Delaney have already joined the black and yellows, with a few more arrivals expected in the coming weeks.