According to Chelsea's chief executive Ron Gourlay, Thibaut Courtois is able to face Chelsea in the Champions League semi-finals. The Belgian goalkeeper is on loan from Chelsea and has been crucial to Atletico's success this season as they are among Europe's finest four for the first time since 1974.
However, Friday's draw paired the two clubs and Chelsea were warned by UEFA they could face sanctions if Courtois is not allowed to play for Atletico.
Gourlay says Chelsea won't stop Courtois from playing against them, but didn't go as far as to mention whether Atletico would have to pay them a fee or not.
"The loan was arranged back at the start of the season," Gourlay told Sky Sports News. "It's quite simple - Thibaut can play against Chelsea. That was never in doubt.
"Regarding the UEFA statement, we'll evaluate that in due course. As far as Chelsea's concerned, we've complied with the loan rules."
Meanwhile, Atletico director Clemente Villaverde has said UEFA regulations allow Courtois to play against Chelsea without any fee having to be paid, however, he didn't confirm that Courtois would actually play both matches.
Villaverde, who reportedly met with UEFA officials before the draw was made to discuss the matter, told Spanish newspaper AS afterwards that the competition rules would come before any private agreement between two clubs.
"Courtois would be able to play with a financial penalty, but article three of UEFA's regulations prohibits [that clause]," Villaverde said. "The UEFA regulations are above any agreement with Chelsea. There cannot be limits on costless participation in the competition."
Should Thibaut Courtois not feature against Chelsea, Atletico would likely field second choice goalkeeper Dani Aranzubia, who has played only twice this season. Aranzubia has had mixed results this season as he saved a penalty in the 2-0 win over Porto in the group stages, but was then sent off in a La Liga match against Almeria as Atletico lost 2-0.