Ten-man Freiburg halted Borussia Dortmund's promising start to the season Saturday in a 0-0 Bundesliga draw and also added to the team's injury list.
Dortmund defenders Marc Bartra and Marcel Schmelzer went off in the first half and are doubtful for the Champions League opener at Tottenham on Wednesday.
Tim Kleindienst had the best early chance for Freiburg but failed in a one-on-one with Dortmund goalkeeper Roman Buerki.
Dortmund dominated possession afterward but lost Bartra and then Schmelzer as the home side pulled no punches.
French midfielder Yoric Ravet was sent off on his Bundesliga debut for a cynical challenge on Schmelzer after referee Benjamin Cortus consulted with his video assistant. Cortus at first showed a yellow card but TV replays showed Ravet stamped on Schmelzer's right ankle.
Freiburg coach Christian Streich applauded sarcastically, but Schmelzer was unable to continue. He was replaced by new signing Dan-Axel Zagadou.
Down to 10 men, the hosts sat back, stayed compact and defended with every man they had.
Dortmund are yet to concede a goal after three games but dropped points for the first time.