NSW centre Tom Carter described as ''rubbish'' claims Folau was underwhelming at fullback while coach Michael Cheika vowed he would continue to ''invest'' in his marquee signing.

''I have a different expectation, everyone think he's going to come out and no one's going to touch him, he's going to run through and score every time he gets the ball and that's ridiculous,'' Cheika said. ''I understand we've got to invest in him in these matches to get the best out of the player in the longer term and that's what we're going to do.''

Folau was by no means a liability for his new teammates, scoring the try that started the Waratahs' second half comeback at Suncorp Stadium.

But he was also part of the Waratahs' defensive problems, failing alongside Adam Ashley-Cooper to pull up Reds winger Dom Shipperley as he bolted for the line in the sixth minute.

''It was exactly where I saw he would be, maybe a couple of little decisions that he could have made better but [that was] no different to any other player in the game,'' Cheika said.

Reds coach Ewen McKenzie said he was happy with his side's efforts to contain Folau.

''He scored a try but I thought we handled him pretty well,'' McKenzie said. ''We forced a few errors from him and he knew he was in a game.''

Folau said he was ''disappointed in my performance'' and had plenty of homework to do before the Waratahs host the Rebels at Allianz Stadium on Friday. But Waratahs veteran Carter said no one was doubting the fullback's potential.

''I think we all contribute to the team's result and effort and I think he'll be an incredible player for us,'' Carter said. ''I think it's very easy for the media to take potshots at him, he's a superstar and he achieved a lot in his very short period of time [in rugby] and we'll stand by him and believe in him and he'll win us some incredibly big games later on in the year. I think [the criticism] is absolute rubbish.''

Cheika did put on notice his back three as a whole, saying Folau and wingers Drew Mitchell and Tom Kingston were not ''potent'' enough.

''We had a bit of ball we could have counter-attacked from and it's early days still for our counter [attack] and I want to be really potent there so that's something we're going to have to work on, to be really dangerous back there,'' he said.

The Waratahs are not short of outside backs, with Wallaby Lachie Turner and rookie Michael Hodge missing out on spots in the match 22 and Peter Betham, who impressed for the Tasman Makos in the NPC last year, unavailable through injury.

Ashley-Cooper and Berrick Barnes, both of whom will be assessed on Monday to decide their availability, are also options at fullback.

''I've said the whole time the back three is totally interchangeable, it's more about the combination of players we play back there,'' Cheika said.

''Some guys missed out very narrowly this weekend so we'll have to have a look and see but there's none of that 'from that performance your starting spot is in peril' [being said]. We're a team that is going to build up together. Sometimes people will feel the pain but not at the moment, we're still about getting ourselves accountable for some of those things first.''