After losing Heung-Min Son to Tottenham, Roger Schmidt has signed the former Red Bull Salzburg star from BVB.
Bayer Leverkusen has completed the signing of Kevin Kampl from Bundesliga rival Borussia Dortmund.
Kampl makes the move to the BayArena on a deal that ties him to the club until 2020 and sees the Slovenia international return to a team with which he spent much of his youth career.
The midfielder originally joined Leverkusen in 1997, but left in 2011 after making just one senior appearance.
Following spells with Onsabruck, VFR Aalen and Red Bull Salzburg, Kampl made the move to Dortmund in January, but he leaves Signal Iduna Park having featured only 19 times.