Substitution cock-up could cost Bayern Munich
Bayern Munich only played with 12 men for a matter of seconds, but the rule infraction could see the Bundesliga leaders stripped of victory.
The leaders were 3-1 ahead and on the way to a 4-1 away victory when head coach Julian Nagelsmann elected to make a late double change, removing Corentin Tolisso and Kingsley Coman and sending on Marcel Sabitzer and Niklas Sule.
However, Coman did not realise he was being replaced after his number was not raised, and he did not leave the field immediately, with referee Christian Dingert resuming the game before this was noticed.
The game continued for several seconds before being halted as all concerned attempted to make sense of the situation, and the incident may even see Bayern forfeit the win.
German football association (DFB) rules appear to suggest Freiburg could be declared 2-0 winners.
According to paragraph 17, article 4 of the rulebook: "If a player was not eligible to play or be fielded in a game, the team that culpably fielded this player lost the game 2-0 and the opponent won 2-0."
This rule is only to be deployed if the match is allowed to proceed by the referee, as it was on this occasion. A 12th player on the field would be considered ineligible to take part.
Nagelsmann said of the bizarre incident: "The wrong number was on the board, not Kingsley's 11. Mistakes happen. From the point of view of both teams, from the point of view of a fair sport, there was nothing that speaks against it being fair. You play a good game here and then everyone stands there and asks about the rules."
Freiburg coach Christian Streich, appearing alongside Nagelsmann at a post-match news conference, said rules should not be ignored.
Streich said: "I'm sure there won't be an objection, an appeal, from us, but there are rules to be followed.
"There is a rule and there's plenty of speculation, but we have a rulebook and that's what we have to abide by. Everything else, I'm not going to say anything about it, because there's nothing for me to say."
Referee Dingert, quoted by TZ, said: "It was a totally confused situation: It was a double change from Bayern Munich. An incorrect number was initially displayed, which is why the player Coman did not feel addressed with the number 11.
"That's why a 12th player was on the field for a short time, which shouldn't be. We noticed and then stopped the game.
"It's annoying for us because of course that scene is the focus now. We will note this in the game report. The game had 12 [Bayern] players for 15, 16 seconds. No goal happened. We will note that, everything else will be decided by the DFB."
Leon Goretzka, on his return from injury, scored Bayern's opening goal, with Serge Gnabry, Coman and Sabitzer also on target. Nils Petersen's reply was his 100th goal for Freiburg in all competitions.
Victory kept Bayern sitting pretty at the top of the Bundesliga, taking them nine points ahead of Borussia Dortmund who later lost at home to RB Leipzig.