Assessing the form of teams across testing, Norris said: "The Mercedes was 30.0 [best lap of one minute 30.025secs] and Lewis had a few spins, three or four spins or something, so it doesn't look easy for them.
"Even if they were at 50 kilos of fuel, or whatever, they don't look like they had as quite a comfortable pre-season test as they have in the past few years.
"Maybe the shock is the Mercedes, that it's not quite so good as you would expect, but it's pre-season testing, everything is up in the air. No-one really knows what everyone's doing. It's all just a guessing game.
"I don't want to be the guy that says a team is doing bad or good and then they just prove me wrong and make me look like a muppet come the race weekend."
Last season McLaren came out on top from a frantic midfield battle that primarily involved Racing Point and Renault, as well as Ferrari and AlphaTauri on occasion, by finishing third, its best constructors' championship placing for eight years.
Eyeing up the opposition on this occasion, Norris was particularly impressed with AlphaTauri, claiming it "is looking strong".
He added: "Looking at the onboards and seeing the data that we can see, they look like they have a very strong car. It looks very nice to drive. Good in all kind of conditions.
"They look like they had a clean few days, they looked good in every run they did, the long runs as well when everyone knows they’re going to be at high fuel, and so on.
"But everything looks quite close, no-one looks miles ahead. The Red Bull has looked strong over the past few days, and that's kind of expected."
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