Mobile network Three have asked to temporarily suspend their sponsorship with Chelsea after the club's owner Roman Abramovich was added to the UK government's list of sanctions following Russia's invasion of Ukraine.
The 55-year-old is described by the government in the sanction document as a "pro-Kremlin oligarch" who has had close links to Russian president Vladimir Putin for "decades".
And as a consequence Three have asked to pause their deal as the club's shirt sponsors. That is a step short of completely terminating the deal, which is worth about £40million a year, signalling that Three could return if the club is taken over by a new owner.
The club would not be able to use any money made from sponsorship deals while frozen as part of the sanctions.
The announcement comes three hours before Thomas Tuchel's side face Norwich City in a Premier League game at Carrow Road and it is unclear if the mobile network's logo will still appear on the front of their shirts.
A Three spokesperson said: "In light of the government's recently announed sanctions, we have requested Chelsea Football Club temporarily suspend our sponsorship of the club, incluing the removal of our brand from shirts and around the stadium until further notice.
"We recognise that this decision will impact the many Chelsea fans who follow their team passionately. However, we feel that given the circumstances, and the Government sanctions that is in place, it is the right thing to do."
It is expected the car manufacturer Hyundai, whose logo appears on the sleeves of the club's shirt, will also request for their deal to be suspended and others could follow in the next 24 hours.