Blueco's movement for Julio Enciso from Brighton is in danger to collapse.
Enciso would initially join Strasbourg before switching to Chelsea.
The 21-year-old Paraguayan midfielder was set up for a £ 13.8 million switch as part of Blueco's Multi-Club model, where Strasbourg was reserved as his first destination before he finally went to Stamford Bridge.
But the deal can now be questioned in the midst of reports Enciso has a medical failure, although neither Brighton nor Chelsea have publicly responded to speculation.
Enciso entered Brighton from Libertad in 2022 and shown talent flashes in 57 first-team performances, scored five goals and added six assists.
Yet his time at the Amex has repeatedly interrupted by fitness problems. A torn meniscus in August 2023 excluded him for six months and further knee problems required an operation in May, which is expected to keep him aside for a few weeks.
Blueco may have been wary of the prospect of a different setback, with conversations that are thought to be underway on whether the transfer can still be completed.
Enciso has only had a year over his Brighton contract and the seagulls were open to a sale, but doubts about his physical condition could fully cross the move.
If it had continued, the deal would have represented an attack by Blueco on the means of Brighton. Since the control of Chelsea in 2022, the ownership group has already spent more than £ 250 million on former Seagulls -employees and players, in which Marc Cucurella, Moises Caicedo, Robert Sanchez and Joao Pedro were signed, while also walking manager Graha Potter and his staff.
Recruitment heads Paul Winstanley and Sam Jewell later followed from the Amex to Stamford Bridge.
Enciso was intended to become the fifth player who was acquired from Brighton, with Blueco planning to use Strasbourg as his springboard.
The French club was purchased in 2023 and has since become an important part of the pipeline of the talent development of Chelsea. Managed by Liam Rosenior, they started the Ligue 1 season with a victory at Metz and Face Brondby in the Europa Conference League-Play-Off Round this week.
Enciso was set up as a tent addition to strengthen their European campaign.