MADRID, Spain - Lewis Hamilton believes cost-cutting changes will make it tough for him to win the Formula One championship again next year.

FIA, the sport's governing body, and the F1 teams agreed to a series of measures for 2009 on Friday, which include longer-lasting engines, limits on expensive testing and cheaper, off-the-shelf engines for smaller teams.

"I don't think it's going to make it easier," Hamilton said during a conference call Tuesday. "Definitely with the new regulations, it's going to be tough as it is.

"We're working very, very hard on making sure we approach and enter the season with a fighting chance to win the championship again."

Hamilton, 23, became the youngest and first black driver to win the F1 title in 2008.

F1's sweeping changes for 2009 come as automakers reel from the global financial crisis.

Honda pulled out of F1 this month after Super Aguri quit in April. FIA said the first batch of changes for 2009 will help larger teams cut costs by about one-third over 2008.

"We have less testing obviously but I think we as a team are in a position to pull together and make a difference in some other way," Hamilton said. "But everyone's in the same boat."

Changes to be introduced after next season will be even more radical, with races possibly shortened to save money and refuelling banned -- which could dramatically alter the spectacle for fans.

Hamilton's McLaren team boss, Ron Dennis, called it a "challenging period."

"It's amazing how many different things happen in a year but all we're thinking about is how we can continue in the sport and continue to put on a good show," Hamilton said. "How we can move forward and continue to win as a team?"

Hamilton overtook Toyota's Timo Glock on the final bend at the season-ending Brazilian Grand Prix in November to finish fifth in the race, securing the overall title after Ferrari's Felipe Massa had won his home race as he needed.

Hamilton expects more of the same close racing next season despite the dramatic changes.

"We don't know who's going to be quick. Surely we're going to be at the front, with Ferrari maybe, BMW, but you never know," he said. "Maybe there's going to be a fourth team up there with us."

Hamilton added that becoming F1's first black champion "was hard" because of having "to break down the barrier and it was not easy but we got there, and I have been accepted very well into the sport."

Balancing increased commitments from sponsors, the media and fans has become the toughest part of the job.

"There are always going to be pressures there and it's how you deal with them. It's how you rise above it," the Briton said.

Hamilton was in the U.S. on Tuesday to celebrate his F1 championship with McLaren Mercedes partner Mobil 1. He remains hopeful North America would be back on the calendar in the near future. There will be no U.S. or Canadian Grand Prix in 2009.

"(They're) great memories for myself," said Hamilton, who won his first Grand Prix at Montreal last year. "It's always an amazing show when I go there.

"It's just a buzz, really. I hope we can get it back at some stage. I would love to race there again."