Bayern Munich could be deducted points after a mixup with their substitutions during their win against Freiburg on Saturday.
The runaway league leaders were comfortable 4-1 victors away to the European hopefuls on Saturday, but there was a flashpoint late on when they had twelve players on the pitch.
Confusion reigned after the fourth official held up the wrong number on the board when Bayern intended to make a double substitution in the dying minutes. Niklas Sule and Marcel Sabitzer came on, but only Corentin Tolisso left the field because Kingsley Coman did not realize he was supposed to come off.
The referee didn't realize the mistake and continued to play for 17 seconds with the twelve players before Freiburg alerted the officials to the error; the move led to a long delay as Bayern was restored to the correct number.
The result could now be overturned but manager Nagelsmann thinks it was an honest mistake.
"Coco Tolisso had stomach problems and ran into the tunnel. The fourth official showed the wrong number and Kingsley Coman didn't know he had to go off. Mistakes happen," Nagelsmann said at full-time.
"He was eight seconds or so on the field, then, I don't think he even touched the ball. From the point of fair sport, there was nothing that speaks against it having been a fair game," the manager said.
The win saw Bayern extend their lead at the top of the Bundesliga standings to nine points, with second-placed Borussia Dortmund getting thumped 4-1 by RB Leipzig later in the day.