Borussia Dortmund striker Robert Lewandowski has confirmed that he will be joining Bayern Munich next season.

The Poland international will sign a pre-contract agreement with Dortmund's fierce rivals before completing a free transfer in the summer.

Lewandowski was expected to join Bayern this summer but Dortmund held firm, forcing him to spend the last year of his contract at Jurgen Klopp's side.

But he is free to speak to other clubs in January when he will have just six months left on his contract.

He will follow Mario Gotze from Dortmund to the Allianz Arena.