Antoine Griezmann admitted Barcelona must improve after their Champions League stalemate against Borussia Dortmund.
Ahead of the Bundesliga season commencing on Friday, we assess the five best signings made by clubs in Germany's top flight.
Despite being jettisoned by Joachim Low earlier this year, Mats Hummels would still like to play for Germany again in future.
Borussia Dortmund are without Mats Hummels for the DFL-Supercup against Bayern Munich, who welcome back Kingsley Coman from a knee knock.
Mats Hummels is back at Borussia Dortmund for a second spell and Hans-Joachim Watzke is grateful Bayern Munich sanctioned the transfer.
Marco Reus welcomed Mats Hummels back to Borussia Dortmund and said the defender's quality could make the difference in the title race.
After Borussia Dortmund's title tilt fell apart in the second half of last season, Axel Witsel is not about to accept a repeat.
Borussia Dortmund are in talks to extend Mario Gotze's contract, but the 27-year-old is thinking about leaving the Bundesliga.
Niko Kovac claimed Mats Hummels did not want to compete for his Bayern Munich spot.
German defender Mats Hummels has returned to Borussia Dortmund for a second spell. We look at six past examples of players returning home.