A Manchester City fan received a life-saving transplant from his brother - but only after he promised to support rivals United instead.
EXTRACTS FROM THE CONTRACT
To ensure all blue blood will be replaced with RED
All outer clothing to be RED - with hints of white
Interior and exterior decoration of home to be changed to RED
All blue coloured materials to be used as rags to clean up dirt
Contract to be signed and witnessed under RED seal
Martin Warburton, 50, made brother Paul sign a contract - under a red seal, naturally - to the effect that he would change allegiance.
Paul, 59, who is fighting leukaemia, had the stem-cell transplant in Belfast in August - but admits he has mixed feelings after agreeing to the unusual conditions.
"I was really lucky that Martin's cells matched, as some people can have seven or eight siblings and find that none of them matches up," he told the Daily Telegraph.
"But he had to be a Reds supporter, didn't he?!"
As part of the contract, Paul now has to chortle if Manchester City are relegated and join the MUFC supporters' association.
He also has to trip up legendary City "diver" Francis Lee so that - in Martin's words - "you can, for the first time, see him fall over fairly".
Martin said he could barely suppress his mirth at the contract he made his brother sign.
"This was the perfect chance for me to get Paul to stop backing the Blues," he said.
"We made a great joke of the contract but he still agreed to sign it."