Borussia Dortmund will not stand in the way of Lucas Barrios if he decides to seek a transfer in January.
Barrios, a Paraguay international, has failed to get back into the Dortmund team on a regular basis this season after picking up an injury at the Copa America last summer.
The club's top goalscorer in each of the last two seasons has expressed his unhappiness at the current situation and Dortmund general manager Hans-Joachim Watzke admits they may have to consider selling him this winter.
''Obviously Lucas is unhappy when he is not playing,'' Watzke told the Bild newspaper. "I would prefer it if he were to stay, but if he does come to us and say he wants to go then we would have to talk about it.''