Atletico Madrid president Enrique Cerezo is confident that Thibaut Courtois will be allowed to play against Chelsea but admits a deal must first be struck.
The Spanish club was drawn against Chelsea in the semi-final on the Champions League but face the prospect of being without their star goalkeeper Courtois.
Courtois is contracted to Chelsea having signed for them in 2011 but has yet to make his debut, spending each of the subsequent three seasons on loan to Atletico.
Although there is nothing in Uefa regulations that prevent Courtois from playing against parent club Chelsea, it is reported that an internal agreement between the two clubs will see Atletico have to pay the Blues up to £5m.
Uefa released a statement saying that any such agreement would be invalid in European competition, but Cerezo says an agreement must still be met with Stamford Bridge officials.
"I think he’ll end up playing against Chelsea, but only if we reach an agreement with them," Cerezo told reporters.
"We’re gentlemen and we observe everything we sign.
"Courtois is Chelsea’s player and we’re trying to get him on loan for another season.
"I don’t think there will be consequences from Uefa. I think he’ll play, but only with an agreement between both parties.
"If he doesn’t play, [Daniel] Aranzubia will come in."
The Belgium international has been key to Atletico's chances this season having played 47 games in all competitions. Meanwhile his understudy Aranzubia has only played twice.