Borussia Dortmund attacker Mario Gotze could miss this weekend's Champions League final against Bayern Munich after he was forced to pull out of a training session with a hamstring injury.

The German international, who has agreed to join Bayern in the summer, originally picked up the complaint during the second leg of their semi-final tie against Real Madrid.

It appeared that he had won his fitness battle when he returned to light training late last week, but he had to withdraw from today's team session because of pain in his upper leg.

"Mario has felt something again in his hamstring. That is why he stopped. We don't know how bad it is and whether he is still suffering from it," the club's general manager Michael Zorc told Bild.

Dortmund also have a concern over the fitness of Mats Hummels ahead of the match at Wembley. The centre-back has picked up an ankle problem.