Assistant coach Daniel Halangahu said the Waratahs were a wounded animal and the Blues were aware of how dangerous that made them, especially if the Blues were not on their game.
The Waratahs were probably down on confidence but they had enough good players to be able to pick things up, and it needed to be remembered they had scored a lot more points  in their loss to the Hurricanes than the New Zealand teams had scored.
"They have some quality attack, and we clearly need to be on our game in defence," he said.
The Blues were also looking to get their cohesion perfected as they had battled to achieve that in the first quarter in their win over the Rebels in Melbourne.
Several changes have been made to the pack, two of them allowing All Blacks No8 Hoskins Sotutu and prop Nepo Laulala to rest injuries they have been carrying.
"Hoskins has had a huge load, but he's also got a turf-toe issue he's been nursing. With having Dalton [Papalii] back, it allows us to give Akira [Ioane] an opportunity as well. He has been champing at the bit to get a bit more time at No8.
"Akira has been a little unlucky. He has provided a lot off the bench, and only been there because of Tom Robinson's form. We do have a bit of depth in the back row, but you need it, it's such a combative area of the game," he said.
With loosehead prop Alex Hodgman back from suspension they had the chance to move Ofa Tuungafasi back to tighthead and allow Laulala to rest.
Blake Gibson will start on the openside flank with Papalii, and lock and captain Patrick Tuipulotu, on the bench after recovering from injuries.
Jacob Ratumaitavuki-Kneepkens has a chance to make his debut from the bench. The New Zealand Under-20s wing has impressed with his application at the Blues.
"We expect most 19-year-olds to come in and learn the trade, but he's shown enough that we believe he's ready to have a crack," Halangahu said.
"His form through the Blues' 20s programme is part of what got him the nod. He led well and is electric with ball in hand. He's one of these young guys who will try anything. He'll give anything a crack probably on Saturday.
"We'll keep the reins on him, but give him the freedom to play his game as well," he said.
Hooker Kurt Eklund said they wanted to build on their performance in Melbourne.
He and his front-row friends enjoyed their scrummaging effort in Melbourne, an effort that laid the foundation for the backs to unleash later in the game.
"It was fun. It was a little bit touchy to begin with and there were a couple of scrums where we had to iron out the crinkles but once we got our confidence and started going forward it was a bit of fun to be part of," he said.