NSW Waratahs coach Chris Hickey remains hopeful Tatafu Polota-Nau and Benn Robinson will be fit to face the Brumbies in Saturday's crucial Super Rugby clash in Sydney.

The injury-ravaged Waratahs must beat the ACT side at ANZ Stadium to secure a playoff berth as they continued to count the cost of their 33-7 victory last Saturday over the Highlanders.

NSW lost powerhouse No.8 Wycliff Palu for the remainder of the season with a fractured shoulder while hooker Polota-Nau is battling a knee injury and prop Robinson has an ankle problem.

And on Tuesday inside back Berrick Barnes announced that he was taking an indefinite break from the game to deal with head knock-related issues after lasting just 33 minutes against the Highlanders.

"There's a few players who probably won't train until Friday," Hickey said.

"We're still hopeful of Benn Robinson and Tatafu Polota-Nau that they'll be right.

"Lachie Turner (hamstring) is one of those players who may only train on Friday ... very lightly at least on Friday but we're still optimistic."

There was some good news on the injury front for the Waratahs with centre Ryan Cross passing a fitness test.

Cross injured his knee in the loss to the Sharks in South Africa and has missed the Waratahs past two matches.

The Waratahs also have returning Wallaby second-rower Dan Vickerman available for selection.

Vickerman, who last played for NSW in 2008, had spent the intervening period studying in England and only returned to Australia on Saturday.

Hickey is expecting a torrid clash with the Brumbies who are aiming for three consecutive wins after beating Queensland and Melbourne.

"This will be a tough game ... they'll have their agenda and we have our agenda, that's what's most important to us. It's about winning this game and getting a spot in the finals series," he said.

One man capable of preventing the Waratahs from playing in the finals is their 2012 signing Adam Ashley-Cooper.

The Wallabies utility said the Brumbies had plenty to play for after a difficult season.

"The fact that it's my last game with the Brumbies is important to me and it's certainly a special game knowing there's a few other guys leaving next year, so it's the last time we'll be able to play again together," Ashley-Cooper said.

"It would be a shame to go out and make the last two wins a waste.

"All of the guys love playing the Waratahs and they beat us last time at Canberra and with it being up there it would be great to get one back.

"I've alluded to the boys during the week that I'm not a Waratah yet, so I'll be going out there to perform as well as I can."

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