"They are a quality side across the park with mobile forwards; they are excellent at the breakdown and have some world-class running backs.
"We've constantly said that we need to improve week by week and we will definitely need to step up again."
Umaga said he was pleased with the effort from the forwards against the Brumbies.
"The front five laid the platform from which the rest of the team were able to prosper. They will need to be at their very best again in all facets of the game."
The team is facing the second of a challenging six-match run that sees them at home against the Cheetahs next Friday ahead of a one-off trek against the Stormers in South Africa, returning to meet the Chiefs and then travelling to Samoa to take on the Reds.
The Blues team to play the Waratahs at Allianz Stadium on Saturday, kick-off 9.40pm is:
1 Pauliasi Manu, 2 James Parsons (c), 3 Charlie Faumuina, 4 Gerard Cowley-Tuioti, 5 Scott Scrafton, 6 Steven Luatua, 7 Blake Gibson, 8 Akira Ioane; 9 Augustine Pulu, 10 Piers Francis, 11 Rieko Ioane, 12 Sonny Bill Williams, 13. George Moala, 14 Matt Duffie, 15 Michael Collins.
Replacements: 16 Matt Moulds, 17 Ofa Tu'ungafasi, 18 Sione Mafileo, 19 Leighton Price, 20 Murphy Taramai, 21 Billy Guyton, 22 Bryn Gatland, 23 Melani Nanai.