Seoul have been issued with a 100million won (£66,000) fine after a mix-up led them to use sex dolls to fill the space in their empty stadium.
The club mistakenly used the mannequins to fill seats during Sunday's 1-0 win over Gwangju in K League, which has returned behind closed doors amid the coronavirus pandemic.
Seoul apologised for what they labelled "an inexcusable mistake".
Explaining the error, which saw the mannequins supposedly hold up advertising signs for adult streaming sites, the club said the faux pas was down to a mix-up with the manufacturer.
Announcing the sanction in a statement, the K League said: "The disciplinary committee decided to take heavy disciplinary action considering the graveness of the incident, caused by the 'real doll', that has greatly insulted and hurt female and family fans and to prevent similar incidents going forward."