Bayern Munich sponsor Adidas have expressed their discontent after Mario Gotze wore a Nike t-shirt during his official unveiling by the European champions.

The German international completed a big-money move from Borussia Dortmund in April.

However, Gotze's choice of attire for his official arrival at Bayern on Tuesday caused Adidas to label the incident a "...violation of contract, because this was an official FC Bayern Munich event", according to Abendzeitung-muenchen.

Gotze claimed at the press conference that "it wasn't easy" leaving Dortmund.