After Max Verstappen headed a dominant Red Bull 1-2 over Sergio Perez in the season-opening Bahrain Grand Prix, while Mercedes chalked fifth and seventh place, Russell said that he expected the Milton Keynes team to "win every single race this season".
But Mercedes enjoyed a notable jump in performance in Australia after using practice to refine suspension set-up in a bid to make up for time lost to a poor correlation between computer simulations and the car's real-world handling.
Russell and Lewis Hamilton qualified second and third behind Verstappen and both enjoyed spells leading the race, before a power unit failure eliminated the former as Hamilton finished runner-up.
While Red Bull was not as dominant as it had been in Bahrain and Saudi Arabia, the stronger Mercedes showing in Melbourne left Russell to reevaluate his comments that the defending constructors' champion would win every race.
He said of his original claim: "Obviously, after a frustrating qualifying, like the one we had in Bahrain, you say some things in the heat of the moment.
"I do still think Red Bull are a class ahead of everybody else and for sure, Lewis and I got the most out of it [on Saturday in Australia].
"By the sounds of what Max is saying, there was probably still a little bit more in the locker [for Red Bull].
"We're talking that three tenths, is a little bit. Normally, they're a second ahead. Now, they're three tenths ahead. That's still a huge amount in the world of F1."
Russell has talked up the wind tunnel data shown by Mercedes' coming upgrades, although they will not debut until the Emilia Romagna Grand Prix in late May at the earliest.
The team is also working further to refine the mechanical components of the cars to boost both drivers' confidence in the handling.
These step forwards, Russell reckoned, would make him "reassess" if Mercedes can take the fight to Red Bull.
Asked if he had changed his mind on a Red Bull clean sweep, Russell said: "We're not going to give up, we're going to keep on pushing.
"Right now, we'll have to reassess [the claim] when we bring some upgrades to the car.
"That will be the first time when we truly know if they work as we expect and if we can fight them. But yeah, why not."