The former world champion was in contention for a podium finish at Albert Park as he tried to make a two-stop strategy work, but in the end he had to make an extra stop and dropped down to fifth.
Despite losing out on the opportunity of a top three finish, Hamilton was happy with what Mercedes got out of the first race of the season.
"I come away from here really positive," he said when asked by AUTOSPORT for his feelings on the weekend.
"I think for all of us we were not expecting to be competing where we were, and I think we could have done better.
"We definitely had the capability but some things didn't play into our hands. Our understanding of the tyres is now better.
"We take a lot out of here; and in the next race we will be even stronger. I'm really happy with that result.
"Who would have thought that I would be competing at the front when everyone was talking us down?"
Mercedes showed pace over the Australia weekend to confirm it has moved into the battle of the top four teams. But Hamilton thinks his outfit did not show what it was fully capable of.
"I don't feel like I have had a particularly great weekend," he said. "I think it got better towards the end.
"So to still get 10 points, I am really happy with that.
"If we can have that as a baseline and then get 10 points every race, and get better on top of that, then we stand a good chance of getting some good results this year.
"I definitely feel the team is flat out. I feel they are on it and we are going in the right direction.
"Hopefully we have some bits that are coming that can help us make the next step closer to everybody else, and if we can utilise these tyres a bit better we can remain more in the race with the others."
- Sports & Recreation
- Motor Racing