One of the managerial changes before the start of the season was at Borussia Dortmund, who had finished third the previous season. After sacking Thomas Tuchel, they hired the Dutchman Peter Bosz in June 2017, after he had led Ajax to the 2017 UEFA Europa League Final. Dortmund were also the German club involved in the biggest transfer of the summer, selling young French forward Ousmane Dembélé to Barcelona for an initial €105 million. Meanwhile, reigning champions Bayern Munich prepared for the season by breaking the league's transfer record in their purchase of French midfielder Corentin Tolisso from Lyon for €41.5 million.