Bayern Munich attacking midfielder James Rodriguez did not know the score at half-time of their defeat to Borussia Monchengladbach, according to Jupp Heynckes, and will miss training for the next few days after suffering a concussion.
The Colombia international sustained the head injury as Bayern were beaten 2-1, their lead at the top of the Bundesliga cut to three points with RB Leipzig defeating Werder Bremen 2-0.
James, who collided with Tony Jantschke, was replaced by Marco Friedl at the break.
Heynckes said after the game: "He didn't even know the score at half-time. But we have to wait for the diagnosis of the doctors."
Bayern have now confirmed the concussion, putting his place in the team for next Saturday's home game with Hannover in doubt.
A Bayern statement read: "James Rodriguez and Juan Bernat, who had to be subbed off in the 2-1 defeat to Gladbach, reported to club medic Dr Hans-Wilhelm Muller-Wohlfahrt for a thorough examination on Sunday.
"James sustained a concussion when he collided with Borussia's Tony Jantschke. The Colombian will be under medical observation and unable to train for a few days.
"Bernat too will take a short break. The Spaniard sustained a minor muscular problem in his left thigh."