Folau will miss the last-round derby in Brisbane with a corked thigh - Cheika said there was no point risking his attacking ace with the Waratahs having already secured the minor premiership and a home semi-final.

"In another situation, maybe it would have been," Cheika said on Thursday.

"But I'm more than confident with the team that we've got to play well up there."

Cam Crawford will replace Folau, with Wallabies lock Will Skelton to start in the second row instead of Jacques Potgieter in the only other change to the Waratahs side that thrashed the Highlanders 44-16 on Sunday.

Cheika made it clear on Monday that he wouldn't rest any players despite the Waratahs' commanding position entering the finals.

The coach also told his charges he wouldn't risk playing anyone under the slightest of fitness clouds.

Douglas and winger Alofa Alofa were also in doubt but have since been cleared to play.

Cheika said he opted to start Skelton to give him more game time otherwise he wouldn't have started a match for a month by the time the Waratahs host their sudden-death semi-final game at Allianz Stadium on July 26.

Cheika conceded the Waratahs would miss Folau but insisted they wouldn't stray from their successful game plan without the competition's leading tryscorer.

"Of course you lose a lot of attacking prowess, a lot of security under the high ball as well, and a strong defensive man," he said.

"I know there's a lot of talk about winning and losing when Izzy's playing and not playing, but I think we've lost just as many games when he's playing as when he's not playing.

"Even though he's a very strong influence - I'm not going to pretend that he's not - we're comfortable to play when he's not playing the same style as we do normally.

"Rugby's a game of 15 men."

The Waratahs lost two out three games without Folau this season and only two out of 11 when he was on deck.

Most importantly, Cheika was adamant Folau's injury wouldn't linger and that he'd be 100 per cent fit and not underdone for the Tahs' final in a fortnight.

"He's had a lot of minutes this year - and a lot of training minutes as well," he said.

"With the Wallabies, he had a lot of training minutes and we're very mindful of that as we're getting to this part of the year.

"We're getting to 19, 20 games, just making sure that there's a good balance there.

"We've rotated players in an out of training over many weeks just on that odd day here and there just to make sure that they get that chance to breathe." AAP