Manchester United have confirmed they were victims of a "sophisticated" cyber attack but said they are not aware of any breach involving fans' personal data.
The Red Devils confirmed Saturday's Premier League clash against West Brom will go ahead as planned and that all defences needed for the match to take place remain intact.
United also added that the club's media channels were unaffected by the attack.
A club statement read: "Manchester United can confirm that the club has experienced a cyber attack on our systems.
"The club has taken swift action to contain the attack and is currently working with expert advisers to investigate the incident and minimise the ongoing IT disruption.
"Although this is a sophisticated operation by organised cyber criminals, the club has extensive protocols and procedures in place for such an event and had rehearsed for this risk.
"Our cyber defences identified the attack and shut down affected systems to contain the damage and protect data.
"Club media channels, including our website and app, are unaffected and we are not currently aware of any breach of personal data associated with our fans and customers.
"All critical systems required for matches to take place at Old Trafford remain secure and operational and [Saturday's] game against West Bromwich Albion will go ahead."