Lewis Hamilton said his ability to consistently react well to team-mate Nico Rosberg's challenges was the key to his Australian Grand Prix win.

The Mercedes drivers opened the 2015 season with an unsurprising 1-2 on Sunday, as Ferrari's Sebastian Vettel finished a distant third at the Albert Park circuit in Melbourne.

Hamilton made a good start and his lead over Rosberg was around the two-second mark throughout.

The reigning world champion said there was no need to push for a bigger lead, and was pleased he could just hold Rosberg at bay throughout.

"Once you get a two-second gap, you try to manage that. There's no need to eek out more," Hamilton said.

"When Nico turned up the heat, I was able to react to it. Otherwise, it was a phenomenal race for both of us.

"Nico drove very well and Sebastian must've done a great job to be where he is today."

Mercedes' expected dominance was on show as no-one threatened to split Hamilton and Rosberg.

But Hamilton said Ferrari had clearly made big improvements, and he expects Vettel and Kimi Raikkonen to pose his team a serious threat later in 2015.

"I've not seen the times and everything, but I think the Ferraris have taken a huge step forward," he said.

"Clearly they've made one of the biggest steps, so we definitely cannot back off because I'm sure and I anticipate we may have a good fight with them at some stage this year."