NSW stars Berrick Barnes and Wycliff Palu will sit out Saturday's challenging Super Rugby clash with the Blues in Auckland, as the Waratahs continue their no-risk injury policy.

Explosive No.8 Palu, who has played the last four rounds following a lengthy injury layoff, went for a scan on Monday on his hamstring.

"It's a fairly mild strain, which is good news, so it's not significant I suppose, but it looks as though it's probably about enough to keep him out of this week however," Waratahs coach Chris Hickey told AAP on Monday.

"We've still got a long way to go in this competition. As much as we'd really like to have him on board, I think given that, we've probably got to err on the side of caution and get it right this week."

Versatile Ben Mowen is set to switch from blindside flanker to No.8, with Dave Dennis, who impressed off the bench in last week's win over Western Force, likely to start at No.6.

"He (Dennis) has played well of the bench for us, and Benny has played a lot of time at No.8 for us, so if that's the selection that we decide on, that will make it a pretty smooth transition," Hickey said.

Five-eighth Barnes will miss a third straight game following a head knock he suffered against the Brumbies.

Hickey said Barnes was making good progress and an MRI had revealed no physical damage.

"Obviously his welfare is our prime concern so he won't be selected this week, instead he'll train and then we'll reassess him after he gets through his training this week," Hickey said.

"He had an MRI and that was all clear, but it depends on how he feels after he trains and if he's still not feeling right, then that's really the symptom that indicates he's not ready to return."

Hickey was happy with the way Kurtley Beale was playing at five-eighth since switching from fullback and suggested he could stay there for a while.

"He's done a terrific job for us there and I think as he settles into that position week afterweek he'll keep getting better," Hickey said.

He said Waratahs skipper and openside flanker Phil Waugh, who missed the Force game with a calf strain, would be assessed after training on Tuesday.

"He needs to be able to train properly and make sure that's right, because we don't want that to deteriorate from a strain and become a grade one tear or anything else like that," Hickey said.

Waugh's deputy, Pat McCutcheon suffered a corked injury against the Force, but Hickey said the problem had settled down and the youngster would probably train on Tuesday.

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