Lewis Hamilton has said that it’s “impossible” to be friends with Nico Rosberg as the two Mercedes drivers battle for the Formula 1 drivers’ championship. With Mercedes becoming the sport’s dominant team, the duo have battled for the title for the past two years, each time with Hamilton coming out on top. This season, though, Rosberg has won the first four races to open up a 43-point lead over Hamilton heading into this weekend’s Spanish Grand Prix.

Despite being friends on the international karting circuit as teenagers, sharing hotel rooms and pizzas, their relationship has become increasingly strained competing for superiority in Formula 1. After clinching the title at the United States Grand Prix last year, Hamilton dismissive tossed a second-place cap at Rosberg, which the German promptly threw right back. And, talking to "In Depth with Graham Bensinger," he explained that the prize at stake for both men meant a close relationship was out of the question.

“I don’t think it’s possible,” the 31-year-old said. “We have completely different lives. We do different things, Nico’s married with a kid and grew up in a lot different area than I did. He’s a lot different than back them. The reason we got on so well [as kids] is because I was crazy and he happened to do some of the crazy things that I did too. So we kinda got along well. And now he doesn’t do any of those crazy things that I do and I still do all those crazy things. So naturally we’ve gone different ways and different dynamics.

“With the intensity of a battle like we’re having, it’s impossible to have that relationship. You can’t be friends [say], ‘Yeah, yeah win the world championship, no problem buddy.’ That’s not how it goes. Win the championship, that’s all that matters.”

Hamilton has been plagued with reliability, and particularly engine, issues in the opening races of the season, leading some to even speculate that Rosberg was being favored by the team. However, in an open letter, Mercedes emphatically denied those accusations last week.

Still, while 17 races of the season remain, it leaves Hamilton with a significant gap to overcome if he is to make it three world titles in a row and four overall. However, counting in the Briton’s favor is that he believes he is now far more capable at overcoming disappointment than earlier in his career, as he described while recalling one particularly painful failure.

“I would just have like the biggest headache and just like you’re under the biggest dark cloud,” he said. “And I was in my hotel room for three days. I didn’t leave my hotel. I didn’t eat – hardly ate. I just stayed in silence. And I guess just trying to wiggle my way out of this negative head space. At that point in my life I was just so stubborn, and so set in my ways that I couldn’t get past things.

“I think I matured a huge amount. It takes me no time at all to get past things. And that’s been a huge release and it’s helped me raise my level again by quite some way I think. I actually really enjoy the times I don’t succeed. When I came third [in Bahrain, in April]at the time I was fairly short about it. Next day you feel that churn in your gut and you go and train and you use that energy and you grow.”