Hamilton vows 'no holding back' in his 20th Formula One season

The 41-year-old Briton, who has won a record 105 Grand Prix, will line up this weekend where it all began for him in Melbourne with McLaren in 2007 for what will be his 381st race.

The seven-time world champion failed to muster a single podium last year for the first time in his legendary career as he struggled to adapt to his new surroundings with the Scuderia.

But he is entering the new season in a positive frame of mind, taking to Instagram this week to reflect on his long career in the sport.

"Twenty seasons as an F1 driver. It's hard to even grasp the reality of that number," he said.

"It started with a dream. A dream some called ridiculous and said would never amount to anything. Despite that, the dream never changed, and I never stopped chasing it.

"There will always be people who doubt you, people who try to block you, but you can't ever stop fighting," he added.

"I'm forever grateful for the lessons, the quiet moments, the chaos, and the many people who helped me chase and achieve my dreams.

"I'm grateful for the doubters and for the ones who tried to knock me down, too. I'm still here, 20 years on, still standing, still hungry, still focused on the dream. No holding back."

Every car on the grid this year has undergone radical alterations since the end of last season following dramatic regulation changes to chassis, engines and aerodynamics.

It makes the season-opening race in Melbourne one of the most anticipated in years, given the uncertainty of what to expect.

Pre-season testing at Barcelona and Bahrain suggested that the big four -- McLaren, Ferrari, Red Bull and Mercedes -- would again dominate.

Ferrari team chief Fred Vasseur said they gathered "a great deal of useful information" in Bahrain and were confident of a better year ahead.

"Conditions at testing are never really representative and Melbourne will be the first real opportunity to assess how competitive we are compared to our opponents," he said.

"As usual at the start of the season, there are a lot of unknowns and we will approach the weekend with focus and humility."