Chelsea are resigned to confronting Thibaut Courtois in the Champions League semi-finals, though any attempt by Atlético Madrid to renege on a financial agreement that means the Premier League club are due €3m (£2.5m) each time the Belgian plays against his parent club could dash the Spaniards' hopes of securing the goalkeeper on loan again next season.
Courtois is in his third season and a clause was inserted into the latest deal stating Chelsea would be due a fee if he 21-year-old he featured directly against them. Atlético's president, Enrique Cerezo, made clear this week his club do not have the funds – potentially amounting to €6m – to honour such an agreement, prompting Uefa to issue a statement ahead of before Friday's draw in Nyon stressing the need to maintain "competition integrity".
The governing body insisted any "private contract" between clubs which might influence the other's team selection is "null, void and unenforceable so far as Uefa is concerned", with any attempt to enforce such a clause a "clear violation" of the regulations, which would prompt sanction. Atlético's stance remains that neither they nor Chelsea will fail to comply with a Uefa regulation and, despite suggestions in Spain to the contrary, the player is expected to start in the first leg, on 22 April.
The Chelsea chief executive, Ron Gourlay, has confirmed the player is free to feature against his parent club, "if selected by the Atlético manager", but there is intense frustration at Stamford Bridge that Atlético chose to make the private and confidential arrangements within the loan agreement public. The situation is complicated by Chelsea's interest in Diego Costa, whom they will attempt to sign this summer, and their desire to secure Courtois on a new five-year contract – the player's current deal expires in 2016 and he is desperate to play in the tie, and would be unimpressed if he is were effectively priced out of featuring.
The pursuit of the Brazil-born Costa, together with the Spanish club's desire to sign Courtois on another one-year loan deal, have left both hierarchies seeking a compromise on what has become a politically awkward situation, and there remains leverage for an agreement to be reached behind the scenes. Talks between the clubs are understood to be continuing, yet Chelsea have made it quite clear to their counterparts that they would be reluctant to negotiate in future with clubs who renege on established deals.
"The loan was arranged at the start of the season and it is quite simple: Courtois can play against Chelsea; that was never in doubt," said Gourlay, who attended Friday's draw. "Regarding the Uefa statement, we'll evaluate that in due course over the next 48 hours. But, as far as Chelsea are concerned, we've complied with the loan rules. The player can play against Chelsea, if selected by the Atlético Madrid manager."
Chelsea's Premier League game against Sunderland has been brought forward 24 hours to next Saturday, 19 April, to grant José Mourinho's side more time to prepare for the semi-final, with either Carlo Ancelotti's Real Madrid or Pep Guardiola's Bayern Munich, the holders, awaiting the winners in the final in Lisbon next month.