Cassio watches on

Adelaide United will enter its clash against Sydney FC without Cassio but plan to strengthen their squad by using Korean import Shin, former Sydney defender Mark Rudan and possibly Daniel Mullen off the bench.

Adelaide United will enter its clash against Sydney FC without Cassio but plan to strengthen their squad by using Korean import Shin, former Sydney defender Mark Rudan and possibly Daniel Mullen off the bench.

Cassio went down with the flu midweek and was still feeling poorly on Friday. Adelaide coach Aurelio Vidmar saying a lack of preparation ensured he'd be left out of the side.

"He hasn't trained for three days now so we are not going to take the risk, let him recover and get him right for next week," Vidmar said.

"There must be something going around because Hughesy (Adam Hughes) last week had a tummy bug during the course of Friday's game and also (Kristian) Sarkies a couple of days ago felt a little bit of a virus or tummy bug so there is something around."

The 29-year-old's experience will be missed and has prompted the Reds to bring its off-season signings into the fray.

Last week the team got away with having three emerging players - Michael Marrone, Joey Costa and Frankie Monterosso - on its bench.

While Marrone and Costa got some valuable game time, Vidmar has decided to bring more credentialed substitutes interstate.

"Yeah, possibly and we've got another day to make that final decision so we've got some options, Daniel (Mullen), Rudan," he said.

"We'll need a little bit more experience going into a game like this."

With Shin's transfer finally completed, the Reds are looking forward to seeing what the evasive midfielder can produce.

Vidmar said the 20-year-old would be used as an impact player if the team was struggling in the second half.

"We know he had some fantastic qualities and I'm keen as everyone else to chuck him in there but we've got to be mindful we don't chuck him in too early," he said.

"He's got that ability that he can make things happen in the front third and at this point of time what we are looking at, with the game slowing down with 20 minutes to go, then certainly he's got that ability to get past people and make things happen."

Shin has come directly from university football in Korea and has never played in a professional team. Vidmar said his time at Hindmarsh had tested his fitness and character.

"We spoke to Shin last week about being in a new country, new environment and getting used to full-time football. Although he trained every day in Korea the intensity, the training sessions, the loads are completely for what he was used to," Vidmar said.

"He came here not in great condition (but) he's pretty resilient and tough mentally so he pushes his way through everything. In the last week or so he's been reporting he's got heavy legs and sore legs so we've got to mindful as well we don't kill him."

Fleet-footed and skilful, the Seoul-born competitor is sure to be a target of physical defenders. But Vidmar said Shin was bracing himself for that too.

"I think he knows that because the friendly game he played against Perth he got cleaned up a couple of times really nastily in the middle of the park. I said he's tough and resilient, he picked himself up and got on with it so he's got a great mentality," he said.