Already massively indebted, Manchester United faces the prospect of starting next season without a shirt sponsor.
Vodafone's £9m-a-year deal with Man Utd comes to an end this season. The club has been seeking a new backer but has so far failed to secure a deal.
Football clubs have a tight timetable when negotiating with sponsors, usually needing to agree a deal by the end of March at the latest to give kit firms time to produce the replica strips.
A Man Utd spokesman insisted the club was not constrained by deadlines, noting that Italian club Juventus's £15m-a-year deal with Tamoil was not finalised until June.
However, Man Utd has a bigger brand than its rivals and supplies a lot more replica kits, which are sold across the world.
"If you are West Brom, you don't have to produce as many shirts as Man Utd," said one industry expert. "There's more pressure for them and the end of March is pretty tight. The number of people that wear their shirts is just huge compared to everyone else."
A shirt sponsor is usually a club's most lucrative commercial deal. Chelsea recently signed an £11m-a-year contract with Samsung, while Arsenal's deal with Emirates, which includes naming the club's new stadium after the airline, is understood to be worth a total of £100m.
Man Utd was taken over by US tycoon Malcolm Glazer and his family in 2005, and its debts now total around £235m.
But it is understood that the club is prepared, if necessary, for its players' shirts to be logo-free. "The team will go out without any sponsor if the right deal cannot be found," said a source close to Man Utd.
"It's about building a strong relationship. If they don't find a suitable sponsor, they don't find a suitable sponsor."
Man Utd had been in talks with South Korea's LG, but a spokeswoman for the electronics giant said negotiations had come to an end. "I can definitely confirm that we're not going to be sponsoring them."
The club, currently second in the Premier League, was also thought to be close to securing a £60m agreement with online gaming company Mansion, but a deal has yet to emerge.
Talks are also thought to have stalled with Etihad Airways, the government-owned national airline of the United Arab Emirates.
A Glazer family spokesman said they were "confident of a positive outcome".
"Manchester United are actively searching for a new shirt-sponsor deal and an announcement will be made when that's in place," he said. "But there's no issue about timing. The only imperative is that we get the right sponsorship partner."Reuse content