Cyberhackers almost cost a Premier League club £1 million in a transfer deal when an email from the sporting director was hacked, according to a report from the National Cyber Security Centre (NCSC).
NCSC have since urged sports organisations to pay more attention to the threat, adding that it is growing across all sports.
"Sport is a pillar of many of our lives and we're eagerly anticipating the return to full stadiums and a busy sporting calendar," NCSC director of operations Paul Chichester said.
"While cybersecurity might not be an obvious consideration for the sports sector as it thinks about its return, our findings show the impact of cybercriminals cashing in on this industry is very real.
"I would urge sporting bodies to use this time to look at where they can improve their cybersecurity -- doing so now will help protect them and millions of fans from the consequences of cybercrime."
The report showed that 30% of hacks caused financial damage, with one loss at £4m, while a ransomware attack at a Football League club almost caused a fixture postponement as security systems were cut off and a turnstile was blocked.