The German defender has criticised his team-mate for being "stupid" during the club's 1-0 defeat at Borussia-Park
Borussia Dortmund centre back Mats Hummels says Mahmoud Dahoud "screwed up big time" and can have "no excuses" after his red card against Borussia Monchengladbach.
Dortmund slipped to fourth in the Bundesliga standings after losing 1-0 at Borussia-Park on Saturday, with Denis Zakaria netting the winner for Gladbach in the 37th minute of the game.
The visitors went down to ten men shortly after the goal as Dahoud was shown a second yellow card, and they were unable to claw their way back into the game much to Hummels' frustration.