Mourinho is expected to replace sacked Louis van Gaal, with talks ongoing between his agent Jorge Mendes and United officials.

But it has emerged that Chelsea still own the 'Jose Mourinho' name as a trademark - meaning United may need to pay a six-figure sum for the rights.

However, the issue will not scupper any deal, which is expected this week.

Discussions will now enter a third day, despite the deal to bring the 53-year-old former Chelsea boss to Old Trafford being largely complete. On Wednesday, Mourinho told waiting reporters at his home in London that he was going to Portugal.

What is the hold-up?

Chelsea registered both the name Jose Mourinho and his signature as a European trademark in 2005, meaning they can use it to sell merchandise such as toiletries, technology, clothing and jewellery.

Sports lawyer Carol Couse told BBC Sport it was "really unusual" for an individual not to own the trademark to their own name.

"Chelsea could be earning revenue every time someone uses Mourinho's name. It could prevent United from exploiting his signature," said Couse, of law firm Mills & Reeve.

"One of the things United will be looking to acquire is not only Mourinho's image but also his name.

"If United had a brand of Mourinho clothing it would be in breach of the trademark Chelsea currently own."

What are the possible solutions?

Mourinho cannot override the trademark, so the options are:

United do not use Mourinho's name against the exhaustive list of items that Chelsea have registered - from umbrellas to watch straps, lingerie and talcum powders.

United pay Chelsea for a licence so they can use Mourinho's name on club merchandise

United ask Mourinho to buy the trademark back

United challenge trademark if they can prove it has not been used by Chelsea

"That would be pretty costly," said Couse, who estimated the fee for a licence as "hundreds of thousands of pounds".

"Look at the value of the deals that have been done for Mourinho to date. What would be the value of a Jose Mourinho watch?

"He has managed Inter and Real since then. They have either acquired the rights from Chelsea or managed the use of his name.

"If Chelsea didn't grant a licence, every time United used Jose Mourinho's name in a commercial capacity against those products, Chelsea could sue Manchester United. I would suspect United would rather just pay a licence fee."

Any other issues?

There is also potential conflict between Mourinho's personal deals - such as his one with car manufacturer Jaguar - and United's shirt sponsor agreement with Chevrolet.

"I don't think that in itself would hold up any negotiation," Couse explained. "A lot of world-class players go to Manchester United with their own personal deals. Mourinho's deals will be in a personal capacity."

Couse said United cannot force Mourinho to drive a Chevrolet car, for example, or wear Chevrolet clothes outside of club capacity, but they could pay him an incentive to buy out the Jaguar deal early.

Chelsea declined to comment when contacted by BBC Sport.

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(BBC)