Madrid: Atletico Madrid goalkeeper Thibaut Courtois will be free to face his parent club Chelsea in the Champions League semi-finals, UEFA claimed on Friday.
European football's governing body said that any provision in Courtois' loan agreement preventing his participation is against the competition's rules.
"Both the UEFA Champions League and the UEFA Disciplinary Regulations contain clear provisions which strictly forbid any club to exert, or attempt to exert, any influence whatsoever over the players that another club may (or may not) field in a match," they said in a statement.
"It follows that any provision in a private contract between clubs which might function in such a way as to influence who a club fields in a match is null, void and unenforceable so far as UEFA is concerned."
Atletico director Clemente Villaverde confirmed that he had met with UEFA officials to clarify the situation and that the Belgian international would be free to play without the Spanish side having to pay an extra fee to Chelsea.
"Courtois could have played in any case, it was just that there was a penalty clause in the contract if he did," he told Canal Plus.
"Effectively the rules of the competition are established by UEFA and the statement from the committee was a warning that there would be a violation in the case that the player wasn't allowed to play freely."
Chelsea chief executive Ron Gourlay later insisted there was no dispute.
"The loan was arranged at the start of the season. He could play against Chelsea - that was never in doubt," he told Sky News.
Courtois has been a key player as Atletico progressed to the semi-finals of the competition for the first time in 40 years by knocking out Barcelona with a 1-0 win in their quarter-final, second leg on Wednesday to seal a 2-1 on aggregate victory.
However, Atletico president Enrique Cerezo had told Spanish radio station Onda Cero after that match that his side would have to pay "a lot of money" for Courtois to face Chelsea due to a provision in his contract, estimated in the Spanish media be three million euros ($4.17 million) per match.
Courtois has already faced Chelsea once as an Atletico player in the European Supercup last season as the Spaniards ran out 4-1 victors.