Louis van Gaal’s defensive concerns could deepen after it emerged that the Premier League are yet to sign off on Marcos Rojo’s transfer, partly because of Sporting Lisbon’s involvement with funding group Doyen.

Rojo moved to United for £16million eight days ago but has not yet played for Van Gaal. It had been thought that obtaining a work permit was the only delay in his registration being ratified but Sportsmail understands that the Premier League are still processing the paperwork associated with Doyen’s claim to 75 per cent of the transfer fee.

The delay would need to be overcome by 12pm on Friday if Rojo is to be eligible for the important encounter with Burnley at Turf Moor on Saturday afternoon. It is uncertain whether that will prove the case.

Move: Marcos Rojo was unveiled by Manchester United last week after his £16m move from Sporting Lisbon

Theatre of Dreams: Rojo could make his debut against Burnley if the Premier League ratify his transfer

When Rojo was bought by Sporting from Spartak Moscow for £3.5m in 2012 Doyen are understood to have loaned the Portuguese club most of the money.

In return the investment fund would receive 75 per cent of any future transfer fee or be repaid in full at a set interest rate – as with a lending bank. But a row between Sporting’s new president Bruno de Carvalho and Doyen broke out when he discovered the arrangement and claimed the club were being put under pressure to sell Rojo to United.

Doyen insisted this was never the case but in the end the Argentina international did switch to Old Trafford. Sporting received £8m immediately, with two further instalments of £4m due but Sportsmail understands Doyen have yet to receive a single penny and are considering legal action that could end up in court.

United are not implicated in this in any shape and Doyen’s only concern is holding Sporting to the contract the club signed in 2012.

In training: Manchester United boss Louis van Gaal speaks to his new signing during training

That wrangle in itself is not holding up the Premier League’s legal team but any transfer involving third-party entities is looked at with great care after the Carlos Tevez affair.

On a similar basis it took time for deals to be completed for Manchester City’s Eliaquim Mangala and Liverpool’s Lazar Markovic earlier in the window as guarantees on the ownership of their economic rights were sought.