Russell was the far happier of the two after the changes applied to his W14 between the first and second sessions at Melbourne's Albert Park worked. Hamilton's mood was in stark contrast.
“The morning was good, the afternoon wasn't so good,” was the blunt assessment from the seven-time F1 champion.
Hamilton was second quickest in FP1, 0.433s adrift of Red Bull's reigning champion Max Verstappen, with Russell ninth, 0.909s down.
The second session was affected by rain, with only the first 15 minutes run on dry tyres, but affording Russell enough of a feel of his car to put a smile on his face.
For the most part, the standings – with Russell fourth and Hamilton 13th – were irrelevant as no driver was able to set a flying lap on the soft tyres, as would normally be the case.
Hamilton, though, was far from content with the feedback from his car. “It felt a little bit better this morning,” he said.
“We made some changes, (they) didn't work, so we'll revise those tonight. It rained, obviously, so it wasn't the greatest of sessions.”
As to his expectations for qualifying, Hamilton added: “Well, we won't be competing against the Red Bulls.
“It will just be about trying to get up as high as possible. I think we've got the pace to be around fifth, the same as the last race.”
Russell “happy” after Mercedes makes “good steps”
Russell, describing that prediction as “a fair assessment”, at least knows he has a decent car underneath him.
“FP2 was obviously a little bit frustrating for everybody with the weather coming in a little bit surprisingly,” said Russell.
“But it was a reasonable session for us. We definitely made a step from FP1, which is a good thing. We just made a lot of set-up changes over the break.
“We've been doing some good steps recently, we've been changing quite a few things, getting the car into a nice window as the weekend progresses.
“That's quite satisfying sat in the driver's seat, knowing the car feels better, and as a team, we've contributed towards that.
“We'll see how that translates into tomorrow, but definitely in FP1 I wasn't very happy with the car, and in FP2 I was pretty happy.”
As to his own qualifying hopes, Russell added: “If we really put everything together, the third row, between P5 and P8 is where we're looking at the moment.
“Obviously, not where we want to be as a team. We know we've got more to come in a couple of races' time.
“So we just need to maximise our chances, try and have a similar weekend to what we had in Jeddah, where we exceeded the potential of the car, and just keep trying our best.”