Of the Cheetahs, Umaga said: "I'd say we'll probably get a side that's pretty stung after what happened to them at home. They like to throw the ball around. I'd say they would have got good confidence playing against the Highlanders at home and getting so close.
"They'll come with confidence and if they can stick with us, the Waratahs showed we do have some vulnerabilities that we need to work on this week."
Either way, the match against the free-running Cheetahs will not be a low-scoring one, and while the Blues remain the bottom-placed New Zealand side, their attacking ability is such that every team would be right to fear them in this form.
Of their five remaining matches, only one is against a New Zealand team - the Chiefs at Eden Park on May 26.
The concussion to Sonny Bill Williams will be a complicating factor this week, as will a knee injury for back-up hooker Matt Moulds. But on the other hand, left wing Rieko Ioane was too hot for the Waratahs, who included Wallabies fullback Israel Folau, to handle, and Rieko's loose forward brother Akira is showing the sort of form that might be interesting the All Blacks selectors.
"He's making the most of every opportunity he gets," Umaga said of Rieko. "At this stage he's playing on the wing for us, but we know he's a very accomplished centre, too. "It just started raining when we got to the ground so we obviously wanted to change things up a little bit and play more down in their territory, which I think we achieved.
"Our ability to adapt to the conditions was really good. The first 40 minutes was good, we knew they were going to come back, we talked about it, but we went off the boil there."