Isaias was forced off at half-time in the victory at Coopers Stadium and underwent scans over the weekend which confirmed the blow on the eve of the club’s AFC Champions League opener.

Adelaide, who faces Japanese giants Gamba Osaka at Coopers Stadium on Wednesday night, named Isaias as one of their four foreign players for the 2017 ACL, excluding Marcelo Carrusca and Iacopo La Rocca.

“He’s out. It’s possible for three, four or five weeks, it depends,” United coach Guillermo Amor said.

“We’ll wait, less time is possible. He’s very strong and a very good professional. He always starts before when he has a problem because he works a lot.

“If you remember Cirio, he has a problem and he was eight weeks out. Henrique has the same problem and he was six or seven weeks. It’s a similar situation.”

Amor refused to be drawn on Isaias’ replacement in the United starting XI, nor whether new recruits Baba Diawara, Eli Babalj or Kim Jae-Sung would start.

Teenager Riley McGree is one contender to take on Isaias’ role but Amor gave nothing away.

“Tomorrow you will see,” he said. “We have different players who can play in this position. Tomorrow we decide.

“McGree is one option. He can play eight or nine.

“He’s a good option because he’s playing very well.”