Hamilton cut a disgruntled figure on the podium in Australia last week after squandering pole position and finishing third, while team-mate Jenson Button won.
“I was disappointed and I don’t feel I should have to disguise that,” said the McLaren driver, reflecting on the opening race of the 2012 season.
“It’s just that I worked massively hard over the winter, harder than I’ve ever worked, and the result of the race didn’t go the way I wanted it to. But I’m only looking forwards. It’s only one race and I still got 15 points. It’s very early days – another 19 races to go.”
McLaren outshone champions Red Bull and Sebastian Vettel in Melbourne and are tipped to excel again in Sepang, a track similar to Barcelona, where they performed well in pre-season testing.
But Button has warned he expects their biggest rivals, which also include Mercedes and Lotus, would improve on their performances Down Under.
“We’ll be competitive, but you’ll see other teams up there as well,” said the Englishman.
“When Red Bull get their act together – and a few others – they’ll be very competitive.”