They joke about sharing digs and candlelight dinners but the friendship between Red Bull teammates Daniel Ricciardo and Max Verstappen may be put to the test in the Australian Grand Prix on Sunday.

Verstappen, aged just 19, is entering his first full season with Red Bull after replacing Russian Daniil Kvyat midway through last year.

The son of former Formula One driver Jos Verstappen, he made an immediate impact, winning his first race with the team at the Spanish Grand Prix in Barcelona.

With Mercedes driver Nico Rosberg surprisingly retiring after claiming the world title, the contenders are lining up, including the Red Bull duo, who finished third (Ricciardo) and fifth (Verstappen) in the 2016 standings.

Considered as one of the strongest driver line-ups on the grid, Ricciardo, who crossed the line fourth at Albert Park last year, said that so far things were sweet.

And so it seemed given their banter.

"We've been on six dinners this week," Ricciardo said.

"Romantic ones, as well," Verstappen chimed in.

"We don't share a room," said Ricciardo.

"Yet," added his baby-faced teammate.

Ricciardo admitted that their rivalry may heat up if they are fighting for the drivers' championship, before adding they also had to work together to succeed.

"We both want to win and beat each other, there's no denying that," Ricciardo said.

"But at the same time, we've also got a team that's trying to build fast races and two heads are better than one, so we understand that we're only helping ourselves if we help each other, because then the car's going to be faster and give us a better chance to win."