Waratahs lock Dan Vickerman is in doubt for Saturday night's Super 14 clash with the Bulls in Pretoria after falling ill with a stomach bug.

Vickerman, the NSW lineout general, missed the final training session in Johannesburg.

"We've had a few players suffering from the same illness on tour and Dan is not too well at all," said head coach Ewen McKenzie.

"I'm optimistic about his chances but if he doesn't play we've got full confidence in Will Caldwell and Stephen Hoiles to direct the lineout."

McKenzie said a decision will be made on Saturday.

Daniel Halangahu and Adam Freier both trained strongly on Friday despite also battling illness.

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