Already threatened with the loss of seven league points following alleged financial mismanagement, FC Sion now seem set to lose an additional three points after fielding too many foreign players in Sunday's win over St Gallen.
Sion are currently leading the Swiss top division after winning five of their opening nine matches, but the combined points deduction would be enough to put the canton Valais club second from bottom in the league standings.
The national league originally docked the club seven points in midweek after finding that Sion had failed to produce sufficient financial guarantees for the new season.
Sion immediately launched an appeal and on Sunday appeared to have begun a similar fight back on the pitch with a 1-0 away win over former champions St Gallen.
Six foreign players
But the celebrations came to an abrupt end on Monday when it was discovered that Sion had played four minutes of the match with six foreign players. League rules state that a team can only have five foreigners on the pitch at any one time.
The regulations go on to say that any breach of the five-foreigner rule will lead to the result of the match being overturned with a 3-0 victory being awarded to the non-offending team.
The rule was last applied three seasons ago when Lugano saw a 1-1 draw against Lucerne converted into the mandatory defeat. Two seasons ago FC Zurich dropped into the relegation playouts on the last day of the qualifying round after breaking a similar regulation regarding the number of foreigners allowed on the substitutes bench.
swissinfo with agencies