Canberra United will appeal a ruling which docks the club of three points and puts Sydney FC atop the A-League Women's table.
United have been found guilty of fielding an ineligible player and stripped of the three points for their 2-1 win over the Sky Blues on February 11.
United were found to have used an unauthorised additional substitution by an investigation by Australian Professional Leagues (APL).
The APL scrubbed the result, instead awarding Sydney a 3-0 victory - an outcome which lifts the Sky Blues into first place above Western United.
United retain fifth place on the ladder but are now just one point ahead of sixth-placed Perth Glory.
"The final substitute was made at a time in the game when Canberra had already used all available windows under our regulations," A-Leagues commissioner Greg O'Rourke said in a statement on Monday.
"Whilst it is unfortunate, the league must ensure its regulations are upheld."
United's chief executive officer Ivan Slavich said the club would appeal the verdict.
United allegedly broke rules stipulating clubs can only make substitutions within three specified blocks, unless a substitution is regarded as replacement for a concussed player, he said.
The investigation followed United's use of a fourth substitute in the 93rd minute of their home victory over the Sky Blues.
"It is extremely disappointing to learn that the club will lose three competition points over this matter," Slavich said in a statement.
"We believe that we have not committed any violation of matchday regulations because of advice we received from the match officials during the fixture."
United's appeal will be heard under Football Australia's grievance procedures at a date to be determined.
Canberra have four more games to play before the ALW final series starts on April 15.
