New Waratahs starting centre Morgan Turinui believes the backs will decide on Friday night's Super 12 clash with the Bulls in South Africa and not the hyped-up battle of the forwards.

Wallaby back Turinui was named to replace Ben Jacobs at outside centre for the Pretoria match in his first Super 12 start this year.

Fullback Mat Rogers, who missed the Waratahs' loss to the Stormers last weekend with an ankle injury, has been included but a final decision on whether he will play will be left until game day.

With Matt Burke back in Sydney for the birth of his child, winger Cameron Shepherd will move to fullback if Rogers is ruled out with former Wallaby Scott Staniforth the likely new No.14.

Much has been made of the looming clash between two of the Super 12's best packs but Turinui said they would cancel each other out and the backs would be the key.

"I fully expect our forwards to at least gain parity with their forward pack in all facets of the game.

"I think the pendulum will swing from the backline and I think we have to take them on out wide and if we can win it there, I'm sure with the way our forwards play they'll have us (backs) in the game, so we'll decide who wins."

Turinui's plan may be foiled by forecast thunderstorms over Loftus Versfeld, which may see a repeat of the heavy rain relished by the Bulls in their win over the ACT Brumbies last weekend.

NSW coach Ewen McKenzie said it was "exciting" to pit his side against the Springbok-laden pack, which would give the table-topping Waratahs a measure of their progress.

"There's some talk of rain there but we're not worried about that," McKenzie said.

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