Blues coach Vern Cotter said after their bye week and the earlier big win over the Rebels that the Brumbies would offer different qualities and be a significant hurdle.
The Blues are taking the attitude that every game is different and are trying to work on specific aspects of their game.
"Some things have come through and are positive and growing within the game. It's important for confidence and validating things we are working on.
"But now we go to another strong team on the same points that we are and who have a good draw in the back end of the season.
"This [game] is important, not only on content, but also on the points table."
Cotter said the Brumbies were well-balanced. They were smart and a hard team to break down, with good players and playmakers.
"They have a solid pack and have had that for a number of years.
"It's a cultural thing with them, so we'll have to get into them around certain things.
"There's no easy access points. You've got to work hard to get them, and they stay in the game."
An 80-minute effort would be required because the Brumbies would not go away.
Cotter said Australian teams have shown more fight in 2024 and have more belief in what they're doing.
There was disappointment with their Rugby World Cup effort last year, and Rugby Australia wanted to improve.
"They've sharpened up on all things. They're another year in, and they're better with time spent together and with an improved attitude."
That made it a test of the Blues' mindset, concentration, and ability to stay calm and controlled under pressure while working their way out of situations and making the most of the situations they created for themselves.
Bryce Heem has returned to second five-eighths, and Cotter said he and centre Rieko Ioane have played a lot together and are getting better as the season continues.
"They complement each other, they're tough defensively. Against a good team like the Brumbies you need experience and they have that experience in the midfield."
Lock Sam Darry returns to play after an injury and will be on the bench.
"He's like everyone that's come back after a long injury. We could have brought him back two weeks ago, but he benefited from another two weeks preparing and he's in a good place."
Captain Patrick Tuipulotu has recovered from concussion and said that while his broken jaw and time off after his HIA was not ideal, he was feeling fresher than he might otherwise have been.
That is important because the Blues have a tough run into the finals. He said there were signs the Blues were starting to play to their potential, but they were always searching for the perfect 80-minute performance.
"We haven't reached our potential. We've trained well and improved steadily throughout the first half [of the competition], but as we come up against these top teams, we'll test ourselves and gauge where we're at."
Much of that improvement depended on discipline and not giving away penalties that let opponents back into games.
The Brumbies are a set piece-oriented side who are playing well.
"They play a very physical game up front, and they have fast backs who can finish out wide. For us, it's the battle up front first and foremost, and then taking any bonuses out wide. This is pretty much our Test match."