Lewis Hamilton is predicting a battle royal with Nico Rosberg this season and their fierce rivalry showed no signs of abating in a tense press conference on Friday.
While Sebastian Vettel's ever-improving Ferrari team are expected to lead the challenge to Mercedes in 2016, Formula One is braced for its third instalment of Hamilton versus Rosberg.
Hamilton has triumphed over Rosberg in each of the last two campaigns while sealing consecutive championships.
When describing the car he will use in his quest to win a fourth career world title, 31-year-old Hamilton said: "I think when I first got I was like, 'Jeez, I'm old', because I have been doing it a long time. Physically when you get in the car each time it gets harder and harder."
Rosberg, 30, then said: "Physically harder and harder? Getting old? What is the reason?"
Hamilton, standing metres away from his rival, sniped back: "Crazy, yeah. I have seen some grey hairs on you. You know how it is, you're only six months behind me, man."
It was a spiky exchange between the two drivers that will set the tone for the season which starts in Melbourne on Sunday week.
Hamilton and Rosberg were speaking at the team's annual launch in Stuttgart where Mercedes boss Toto Wolff also revealed the code of conduct between the two drivers would be relaxed this season.
Hamilton and Rosberg clashed at the 2014 Belgian Grand Prix before banging wheels at last year's grand prix in Austin. Hamilton subsequently won the race and Rosberg flung a cap at his team-mate in the green room ahead of the podium ceremony.
"There is no code of conduct and we have reduced it from last year to this year," said Wolff, standing between his two drivers. "When we started the project in 2013 there was a lot of pressure on the team to win races and we have done okay.
"In 2014 we won the championship and we confirmed it wasn't a one-off in 2015. We tried to put a framework around that. Sometimes it functions and sometimes it doesn't.
"They are fighting for the drivers' championship. This is the most important target for them and we cannot expect them to schmooze around. I have no doubt that we will have some interesting moments on track because it is part of the rivalry and part of Formula One but all within the spirit of the team."
Hamilton was sporting his now customary glasses at the event, but the Briton stressed their design was merely for "fashion".
"I think we will have a real battle this season," added Hamilton, who claimed he had "40-40 vision". "I think Ferrari have stepped up their game and made a significant improvement from last year to this year. They did some incredible times in their runs in the last test.
"I think they will bring a good package to the first race, so I think there will be a fight and I am excited about it."
Rosberg, who is out of contract with Mercedes at the end of the year, has finished behind Hamilton in each of their three seasons together with the team.
"He has beaten me in the last three years, so it is going to be a tough challenge but that's the challenge I love," Rosberg said.
"I like going into a difficult challenge against someone who has beaten me over the past three years. It is going to be a good battle and difficult to predict."