Chelsea have launched a clampdown on ticket touts by taking legal action against 11 people, resulting in one being sent to prison.
The tout was locked up for six months for contempt of court in connection with an injunction.
All 11 of the touts have been ordered by Chelsea to pay the costs incurred, amounting to more than £170,000 in total, and have been banned from "loitering or waiting" near Stamford Bridge on matchdays.
Breaching the orders imposed by the court can lead to sanctions, including prison sentences.
The undercover operation, in conjunction with Metropolitan Police, will run throughout the 2019-20 campaign in an attempt to deter others from selling on tickets at inflated prices.
"Ticket touting is known to have links to organised crime," Chelsea said in a statement. "The above action taken against touts operating around Stamford Bridge sends a strong message to others looking to engage in such criminal and anti-social behaviour.
"This football club will not tolerate touting and will continue to identify offenders and take further legal action through the courts to ensure that our club and the surrounding area are safe for our loyal supporters and visitors."