Borussia Dortmund have dropped star striker Pierre-Emerick Aubameyang from their squad to play Stuttgart on Friday for “disciplinary reasons”, the club announced. The Gabonese forward is the club’s top marksman with ten Bundesliga goals so far, but he has failed to score in the past three games with Dortmund in a slump.

“For disciplinary reasons Aubameyang will not feature in the team for tomorrow’s [Saturday] game,” Dortmund said Thursday on the club’s Twitter account. The club, however, made no mention of the nature of Aubameyang’s indiscipline.

After three defeats and a draw, Dortmund have seen their five-point lead atop the Bundesliga turn into a six-point deficit to bitter rivals Bayern Munich.