Manchester United have been hit by a "sophisticated" cyber attack.
The club, who host West Bromwich Albion at Old Trafford on Saturday, say they are confident there has not been a breach of personal data of fans.
United's media channels, the website and the official app are unaffected by the attack.
"The club has taken swift action to contain the attack and is working with expert advisers to investigate the incident," said a club statement.
The club say "extensive protocols and procedures" are in place for such incidents and they had "rehearsed the risk".
"Our cyber defences identified the attack and shut down affected systems to contain the damage and protect data," the statement added.
"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."
United have informed the Information Commissioner's Office and forensic tracing is being carried out in a bid to establish further detail about the attack.
On Saturday, a Greater Manchester Police spokesperson said: "We are aware and currently investigating a cyber-related incident at Manchester United Football Club."
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