After posting the seventh fastest lap in the first free practice, Hamilton could only manage 13th quickest in the second session despite some tweaks to his car.
His teammate George Russell was 11th quickest in the second practice but still more than 1.2 seconds adrift of table-topping Ferrari driver Charles Leclerc.
Hamilton told Sky F1: “It was a difficult session. It’s just nothing you change on the car makes a difference at the moment. That’s the difficult thing. You get in very optimistic and then you make changes and then it doesn’t seem to be wanting to improve.
“And we made some changes going into P2. P1 was better and P2 ended up being a bit harder for me. I don’t know… it’s just a tricky car,” admitted the seven-time F1 World Champion.
In the team report, Hamilton later added: “It’s frustrating because you’re pushing and pushing, and even when you pull off a good lap, you look at the times and we’re over a second down. We’ve got lots of work to do to close the gap.”
Mercedes were wrongfooted by major F1 aerodynamic rule changes this year
Their radically aero-packaged Mercedes W13 car bouncing, or ‘porpoising’, on straights as downforce comes and goes. Making it the worst car of a fine pedigree of Silver Arrows, that collectively gobbled up 17 titles in eight years. This one will be the outcast.
Performance issues led to disappointing results in the first two races in Bahrain and Saudi Arabia, and team boss Toto Wolff said there would be no magic fix in Melbourne.
Russell said his car had the worst porpoising he had ever experienced along the sweeping, lightly curved section of Albert Park where drivers hit high speed before turn nine: “We’re not in the position where we want to be. We need to keep digging into the data and understand.
“We’ve sort of gone from left, right and centre with the set-up and all have resulted in a similar outcome so we need to try and get on top of things and understand why,” added Russell, echoing teammate Hamilton.
Shovlin: We’re finding it hard to generate tyre temperature
Mercedes trackside engineer Andrew Shovlin explained that the problem was getting heat into the tyres: “That’s the big thing we need to work on overnight. We were clearly more competitive in the first session than in the cooler conditions of the afternoon session.
“We’re in a vicious circle where the drivers don’t have the confidence to carry the speed through the faster corners, and it’s that speed that will generate the temperature we desperately need.
“So, not an easy day overall but we’re getting used to those this year. We already have some ideas of which direction we can go with the setup and will do more work overnight in Brackley to understand those changes better, so fingers crossed we can move forward overnight,” concluded Shovlin.
Hamilton has been almost invincible during qualifying in Melbourne over the years, starting from top spot no fewer than eight times. His streak of six successive pole-winning at the venue is sure to end this Saturday. There will be no seventh in a row; can he even make it into Q3? Watch this space. (Additional reporting by Ian Ransom)