German ​Bundesliga outfit Borussia Dortmund have announced the signing of 22-year-old French defender Abdou Diallo from FSV Mainz 

The side, who finished fourth in the German top flight last season, are looking to increase their chances of closing the gap on ​Bayern Munich in the next and are likely to see an influx of player arrivals this summer.

Diallo, meanwhile, spent a solitary season with Mainz after a six-year stint at Monaco, where he started as a 14-year-old. He is also the captain of the France Under-21 squad.

"Borussia Dortmund has signed with Abdou Diallo, a preferred candidate for the defense," Dortmund announced via their official website on Tuesday. 

"The 22-year-old Frenchman changes from league rival Mainz 05 to BVB, at the eight-time German champions he signed a five-year contract dated to June 30, 2023."

"Abdou Diallo brings a great deal of what we expect from access," added club sporting director Michael Zorc.

"He's a modern, strong and very intelligent centre-back. But he can also defend the outside or come in defensive midfield used. The combination of his great potential and his versatility has made Abdou so interesting for us. 

1. FSV Mainz 05 v FC Schalke 04 - Bundesliga

"Diallo's captaincy for France's Under-21 national team also speaks for his qualities as a leader."