Melbourne Rebels coach Rod Macqueen has warned the Waratahs his side are no longer the playthings tossed around on the club's Super Rugby debut.

NSW smashed the Rebels 43-0 in round one - the fledgling club's first match.

Since then the Rebels have won three matches and been reasonably competitive, albeit inconsistent.

Macqueen said the Waratahs could expect a far different performance from his outfit in Sydney on Saturday night than 10 weeks ago.

"We're a different team, there's no doubt about that this time round," Macqueen said.

"(Round one) was a good learning curve for us ... as a team that's struggling to perform week in, week out, it will be good for us."

The Waratahs are coming off a disappointing loss to the Reds last weekend, plus injuries to important players.

Forwards Phil Waugh and Wycliff Palu have been ruled out with hamstring injuries and a serious ankle injury has sidelined winger Drew Mitchell.

Doubts remain over soon-to-be Rebel Kurtley Beale (knee), though he has been named in the side along with five-eighth Berrick Barnes.

Wallaby Barnes is set to resume after a series of concussions.

Macqueen doesn't believe the Waratahs become easier targets with their heavy injury toll.

"They're replacing any of their injured players with Wallabies anyway," he said.

The Rebels have their own injury concerns and will wait until Thursday before deciding whether star backs Stirling Mortlock and Mark Gerrard take their place.

Skipper Mortlock injured his back during the Rebels' 40-23 loss to the Blues last weekend.

Fullback Gerrard missed the match altogether when his hamstring gave way at their last training run ahead of the game.

Both trained with the Rebels on Wednesday in Melbourne.

"They haven't been able to train fully this week and that's why we haven't been able to announce the side," Macqueen said.

"Because we've got a couple in doubt, we haven't been able to settle on what the side is.

"Hopefully we've got our medical staff making a final decision in the morning depending how they pull up after training today."

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