The Sydney Football Club coach, Frank Farina, says they were left with no option but to cut recruit Yairo Yau from the squad, due to complications with a calf injury.
Yau has denied reports he is a long-term injury risk, saying he has not received an official diagnosis.
But Farina says despite the winger outwardly appearing in good shape, he was unable to complete games due to his calves tightening.
Farina says the doctor confirmed it was compartment sydrome, and it became clear Yau was not going to be able to play for the squad during what is a busy and important time of the season.
He says it led to a mutual termination of Yau's deal, with five months remaining on the loan.