Lewis Hamilton v Nico Rosberg: Childhood friends to all-out war

Lewis Hamilton's claims that Nico Rosberg crashed into him deliberately in Sunday's Belgian Grand Prix was the latest incident between the warring duo that has blighted a dominant season for their team, Mercedes.

The two are tussling for the world championship but tensions have grown over the course of the season, boiling up to what is now one of the most fascinating inter-team battles since the fierce rivalry between two of Formula 1's greatest adversaries, Ayrton Senna and Alain Prost.

Here, BBC Sport charts the flashpoints so far in 2014...

Warning signs

It surely had the makings of the perfect partnership. Childhood friends racing for a team that expects to be challenging for the championship.

Bahrain Grand Prix: Hamilton & Rosberg in 'wonderful' duel

Mercedes duo's desert duel

The two are involved in a thrilling duel at the Bahrain Grand Prix in April, with Hamilton coming out on top to win his second race of the year.

Rosberg, though, is not happy with the way his team-mate's victory, claiming the Englishman's move on the 18th lap was "over the line".

The German later plays down any disharmony between the team-mates, adding: "It is not the first time we've had a battle, or the first time it's been a little bit close. We have had so many, right back to 12 years old."

Team radio

Rosberg: "Someone needs to tell Lewis that that move was NOT ON!"

Paddy Lowe, Mercedes executive director (technical), to Hamilton: "Ten laps left to race. Let's just make sure we bring both cars home."

Hamilton adds: "It was a bit more like a go-kart race. I hope there are more races like that through the year."

Cracks appear

The comments about each other become increasingly heated as the season wears on.

The first noticeably tetchy words come in the wake of Hamilton's win at the Spanish Grand Prix in May.

It is his fourth victory in succession and moves him to the top of the championship standings, three points ahead of Rosberg.

After the race, Hamilton says he needs to find a way to break his team-mate's mental strength.

It is a comment that appears to irk Rosberg, who retorts: "Break me down mentally? I think he will struggle with that one."

Coming to a head

Previous on-track tussles and wars of words may have been playfully batted away, but the first real sign of tension between the two comes in Monaco after Rosberg secures pole in controversial circumstances.

Mercedes's Nico Rosberg

Monaco Grand Prix: Nico Rosberg causes controversy in qualifying

After clocking the fastest lap, Rosberg goes off at the Mirabeau corner. Track officials wave the caution flags to slow the cars still out on the track, denying Hamilton the chance to his improve his best time and challenge for pole. The 2008 world champion is furious.

"This weekend went in a direction I wasn't expecting," says Hamilton following Rosberg's race victory.

Hamilton later tells BBC Radio 5 live: "People are always talking about friends, I can count my friends on one hand. I am sure Nico can do the same. I am not in his five and he is not in my five.

"The rest does not matter. We are here to win and here to race, we have a great amount of respect for each other, that is all we need."

Mercedes boss Niki Lauda

"The tension is building up, no question, but the team has to make sure the tension does not get out of hand."

Monaco GP

Hamilton was furious after qualifying for the Monaco Grand Prix.

Friends again

What better way to patch up your differences than on social media? As Hamilton takes to Twitter to reminisce about his long-standing relationship with Rosberg.

Lewis Hamilton and Nico Rosberg

Hamilton and Rosberg back in their karting days

"We've been friends a long time & as friends we have our ups and downs," Hamilton wrote on 30 May:  "Today we spoke and we're cool, still friends #noproblem."

Mercedes

Mercedes on 8 June: "Best... #photobomb... EVER!!! @LewisHamilton @nico_rosberg #F1 #TheMontREALdeal."

Lewis Hamilton on 20 July, following the German Grand Prix: Congrats to Nico winning home race! This c'ship is proving a big challenge but that's how I love it - and I wouldn't have it any other way!

Hungary for more

The niceties do not last for long, though, as the pair go head-to-head again in Hungary. Rosberg is left furious after Hamilton refuses to follow team orders and allow him to pass.

Team radio

Engineer to Hamilton: "OK Lewis, if you let Nico past please. Let him through on the main start/finish straight."

Hamilton: "I'm not slowing down for Nico. If he gets close enough to overtake, he can overtake me."

Rosberg: "Why is he not letting me through?"

Hamilton admits he is "very, very shocked" by the request to allow his team-mate through. He eventually takes third place, with Rosberg finishing fourth.

The German refuses to discuss the incident publicly after the race.

BBC Sport's David Coulthard:

"I think Hamilton is doing what he should do, His exact words were, 'I am not slowing down for Nico', which is right, why should he slow down when he is racing? Nico is just not doing enough."

'Nico hit me, he just hit me'

The mid-season break does little to alleviate any tensions between the two drivers and things come to a head in Spa when the German effectively ends Hamilton's race on only the second lap.

Mercedes' Lewis Hamilton and Nico Rosberg clash at Belgian GP

Rosberg clips Hamilton in Belgian GP

Having locked out the front row with Rosberg on pole, Mercedes are in prime position for a one-two finish.

Those hopes are ended quickly, though, when Rosberg punctures Hamilton's left rear tyre when he hits the back of his team-mate's car at the start of lap two.

Hamilton's shock at the incident is evident when he yells over the team radio: "Nico's just hit me, he's just hit me."

After the race, the two drivers meet Mercedes officials to discuss what happened.

"We had a meeting about it and he basically said he did it on purpose," an incredulous Hamilton reveals.

"He said he could have avoided it, but he didn't want to. He basically said, 'I did it to prove a point'."

BBC F1 chief analyst Eddie Jordan:

"This result means added pressure for Lewis and it will not help in their relationship. It means war. Nico has the upper hand beyond any doubt. I am sure Lewis will come back but he has been fighting an upwards battle all the time and if another error comes up, the championship will go."

Mercedes Formula 1 boss Toto Wolff, who had thought the rivalry would remain civilised, describes the incident as a "decisive moment" for the title fight and the team.

"Lap number two of a long race, a crash between two team-mates," he says. "It is absolutely unacceptable."

After the team's post-race debrief, Wolff adds: "They agreed to disagree in a very heated discussion among ourselves, but it wasn't deliberately crashing. That is nonsense."