Bayern Munich could be in trouble after having 12 players on the pitch for 17 seconds of their win over Freiburg.
The fourth official showed the wrong number on the board which meant Kingsley Coman did not know he was meant to come off in a late change.
Freiburg alerted the officials and there was a long delay and lots of confusion while it was sorted.
Bayern, who are seeking a 10th title in a row, are nine points above Borussia Dortmund with six games left.
However league rules say it is possible this victory could be overturned.
Referee Christian Dingert said it was “totally confused situation [and] now the DFB [German Football Association] must decide.”
Niklas Sule and Marcel Sabitzer both came on in the 86th minute, but only Corentin Tolisso came off.
“We drew the referee’s attention to the fact that Bayern had 11 outfield players on the pitch,” Freiburg director Jochen Saier told Sky.
It is thought they would need to lodge a formal complaint for Bayern to be punished.
Freiburg coach Christian Streich said: “I expect that we will not have to appeal anything. We abide by these rules and that is all I will say about it.”
Bayern boss Julian Nagelsmann said: “The fourth official showed the wrong number and Kingsley Coman didn’t know he had to go off. Mistakes happen.
“From the point of fair sport, there was nothing that speaks against it having been a fair game.”
Leon Goretzka scored on his comeback from four months out with a knee injury for the opening goal when he headed in from Joshua Kimmich’s free-kick.
Nils Petersen levelled seconds after coming on with a first-time finish.
Substitute Serge Gnabry put Bayern ahead again with a good first touch and finish. Coman then drove in from the edge of the box before Sabitzer’s injury-time fourth.
Second-placed Dortmund lost 4-1 at home to RB Leipzig, with Konrad Laimer scoring twice and Christopher Nkunku and Dani Olmo also netting. Donyell Malen scored for Dortmund.
Line-ups
Freiburg
Formation 3-4-2-1
- 26Flekken
- 5GuldeSubstituted forJeongat 83′minutes
- 3Lienhart
- 4Schlotterbeck
- 7SchmidSubstituted forSiquetat 69′minutes
- 8EggesteinSubstituted forHabererat 83′minutes
- 27Höfler
- 30GünterBooked at 70mins
- 9HölerSubstituted forWeißhauptat 83′minutes
- 32Grifo
- 22SallaiSubstituted forPetersenat 62′minutes
Substitutes
- 1Uphoff
- 2Siquet
- 18Petersen
- 19Haberer
- 25Sildillia
- 29Jeong
- 31Schlotterbeck
- 33Weißhaupt
Bayern Munich
Formation 4-2-3-1
- 1Neuer
- 5PavardSubstituted forGnabryat 72′minutes
- 23Nianzou
- 2UpamecanoBooked at 90mins
- 21Hernández
- 6Kimmich
- 8GoretzkaSubstituted forTolissoat 62′minutesSubstituted forSüleat 85′minutes
- 10Sané
- 25Müller
- 11ComanSubstituted forSabitzerat 84′minutes
- 9LewandowskiSubstituted forMusialaat 62′minutes
Substitutes
- 3Richards
- 4Süle
- 7Gnabry
- 18Sabitzer
- 22Roca
- 24Tolisso
- 26Ulreich
- 42Musiala
- 44Stanisic
- Referee:
- Christian Dingert
- Attendance:
- 34,700
Live Text
-
Match ends, Sport-Club Freiburg 1, FC Bayern München 4.
-
Second Half ends, Sport-Club Freiburg 1, FC Bayern München 4.
-
Goal! Sport-Club Freiburg 1, FC Bayern München 4. Marcel Sabitzer (FC Bayern München) right footed shot from the centre of the box to the centre of the goal. Assisted by Serge Gnabry.
-
Attempt saved. Serge Gnabry (FC Bayern München) left footed shot from the right side of the box is saved in the centre of the goal.
-
Attempt missed. Joshua Kimmich (FC Bayern München) right footed shot from outside the box is high and wide to the right. Assisted by Leroy Sané.
-
Attempt blocked. Thomas Müller (FC Bayern München) right footed shot from outside the box is blocked. Assisted by Joshua Kimmich.
-
Attempt missed. Jamal Musiala (FC Bayern München) right footed shot from very close range misses to the left. Assisted by Serge Gnabry.
-
Joshua Kimmich (FC Bayern München) wins a free kick in the defensive half.
-
Foul by Noah Weißhaupt (Sport-Club Freiburg).
-
Attempt blocked. Christian Günter (Sport-Club Freiburg) left footed shot from a difficult angle and long range on the right is blocked.
-
Dayot Upamecano (FC Bayern München) is shown the yellow card for a bad foul.
-
Foul by Dayot Upamecano (FC Bayern München).
-
Noah Weißhaupt (Sport-Club Freiburg) wins a free kick on the right wing.
-
Substitution, FC Bayern München. Niklas Süle replaces Corentin Tolisso because of an injury.
-
Substitution, FC Bayern München. Marcel Sabitzer replaces Kingsley Coman.
-
Lucas Hernández (FC Bayern München) wins a free kick in the defensive half.
-
Foul by Hugo Siquet (Sport-Club Freiburg).
-
Substitution, Sport-Club Freiburg. Janik Haberer replaces Maximilian Eggestein.
-
Substitution, Sport-Club Freiburg. Noah Weißhaupt replaces Lucas Höler.
-
Substitution, Sport-Club Freiburg. Jeong Woo-Yeong replaces Manuel Gulde.