Wolfsburg have signed German international midfielder Julian Draxler from Schalke on a five-year contract.
Kevin de Bruyne watched from the stands as Wolfsburg moved to the top of the Bundesliga with a 3-0 home win over Schalke.
There were Bundesliga wins for Bayer Leverkussen and Bayern Munich, while Wolfsburg and Schalke were held to draws.
Werder Bremen have confirmed Franco Di Santo has activated a release clause in his contract to leave the club immediately.
Bayern Munich will host Hamburg on the opening weekend when the 53rd Bundesliga season gets under way on August 14.
Cologne have signed midfielder Milos Jojic from Bundesliga rivals Borussia Dortmund, the club have announced.