SEPANG, Malaysia (Reuters) - Lewis Hamilton said on Thursday he expected Ferrari to fight back in Malaysia this weekend after the world champions' dismal start to the Formula One season.

"I expect them to be as strong as they were last weekend, but perhaps without the problems they had," the McLaren driver, who leads the championship after last Sunday's win in Melbourne, told reporters at Sepang.

"Hopefully they will have a better weekend. They cannot have a much worse weekend than they had last weekend. I am sure they will recover and do a better job. We will have to watch out for them," added the 23-year-old.

Both Ferraris failed to finish because of engine problems in Australia, although champion Kimi Raikkonen was classified eighth.

With or without a stronger challenge from Ferrari, Hamilton expected another demanding test on Sunday.

"Last year was one of the most physical events that I have ever come across, definitely," said Hamilton, who finished second to Fernando Alonso in a McLaren one-two in only the second grand prix of his career.

"I think a lot of athletes would have struggled in the heat, even if we have a half-dry, half-wet race it will be challenging for all of us. But we are here to win," he added.

Hamilton was confident that he would be even stronger this year after the experience of losing the 2007 title battle by a single point.

"I learnt so much last year, so going into this season I started from a higher point. Overall I was in just much better shape," he said.

"There were a lot of areas last year where everything was new to me so I was always on the limit. Perhaps I consumed more energy mentally and physically than I need to, but this year I have it a lot more under control.

"(In the first race) I just felt like I controlled it a lot better strategically and physically."

Hamilton also said that he will not be pressured into joining the Grand Prix Drivers' Association, despite being urged to do so by retired champion Jackie Stewart to help in the fight to improve safety.

Hamilton has been supported in his stance by Spaniard Pedro de la Rosa, the McLaren test driver who was recently elected chairman of the association and said on Wednesday that he will not try and pressure him to join.

"I am quite comfortable with the way I am," Hamilton said.

"You shouldn't be pressured into doing anything at any point. The great thing is Pedro came out with a comment this week."

(Editing by Alan Baldwin)