Wallabies' prop Matt Dunning is expected to miss the Waratahs' crucial Super 14 rugby clash with the in-form Stormers in Cape Town this weekend.

Dunning suffered a calf injury after playing off the bench in the loss to the Bulls in Pretoria.

The experienced front-rower underwent a scan to ascertain the extent of the injury.

"It has confirmed he has got a strain and he's unlikely to be fit this weekend," a Waratahs' spokesperson said from Cape Town.

He said NSW would not call home for reinforcements as they already had four props in the squad.

Coach Ewen McKenzie named two reserve props in Dunning and Sekope Kepu among five forwards on his bench for the Bulls game.

However, it is understood he will revert to a more conventional 4-3 split for the match against the Stormers.

NSW reported no other significant injury problems, with hooker Tatafu Polota-Nau experiencing no lingering effects from a head knock which caused him to be substituted in last weekend's game.

The Waratahs were scheduled to train Monday and Tuesday and rest on Wednesday in the lead-up to the hugely significant fixture at Newlands.

They enter the penultimate round in second spot, just two points ahead of the fourth-placed Stormers.

A loss could send the Waratahs spinning out of the top four as the Hurricanes (3rd), Chiefs (5th) and Sharks (6th) all play teams in the lower half of the ladder.

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