Adelaide United's FIFA Club World Cup campaign has suffered a blow with the unavailability of Brazilian duo Cassio and Diego. The Reds take on New Zealand's Oceania champions Waitakere United tonight in Tokyo but will be without the two key players.

Coach Aurelio Vidmar has cited a fever for the omission of Cassio.

"Definitely they are out," Vidmar said.

"He wasn't looking good, so we don't take any risk," he said of Cassio.

Diego will miss with a groin complaint but should get up for the next game.

"We thought he would be all right for tomorrow night. But it's still a little bit sore. We really don't want to take a risk," Vidmar added.

"Strong players will come into the squad. We expect them to do their job. For sure, it's probably not our strongest line up, but we've got confidence."