The first race of the 2019 season gets underway in Melbourne on Sunday morning.
Mercedes looks like the team to beat again.
The British driver was fastest by half a second in Melbourne.
The season gets underway Friday in Melbourne.
World champion Rosberg retired five days after winning the title.
The sport is set to undergo some "aggressive" changes.
Hamilton came runner-up to Nico Rosberg in 2016.
Hamilton is a three-time world champion, winning in 2008, 2014 and 2015.
Hamilton is aiming for a fourth world title.