Iran's Sepahan has been stripped of a vital AFC Champions League win and handed a 3-0 forfeit for fielding an ineligible player in the quarter-finals.
The Asian Football Confederation (AFC) erased Sepahan's 1-0 first-leg victory over Qatar's Al Sadd and replaced it with a 3-0 defeat.
The teams play the second leg in Doha on Wednesday.
Sepahan was hit with the sanction for fielding goalkeeper Rahman Ahmadi, who received two yellow cards in separate group games while playing for its Iranian rival Piroozi before switching clubs in the northern summer transfer window.
The AFC said Ahmadi should have served a one-match suspension for the quarter-final's first leg on 14 September, and will now be banned for Wednesday's second leg.
Sepahan was also fined US$1,000 ($1,018).
"The (disciplinary) committee adjudged that Rahman Ahmadi of Sepahan should have served a suspension in the match after receiving two yellow cards during the group stage of the AFC Champions League 2011 when he played for Piroozi of Iran," a statement said.
Sepahan has three days to appeal the decision, which gives it an uphill battle to reach its second continental semi-final after finishing runner-up in 2007.