When Lewis Hamilton joined Mercedes in 2013 from McLaren, it paired him alongside old karting teammate and friend Nico Rosberg. But in the years since, with the team dominating F1, the pair's relationship has been strained and, at times, led to volatile confrontations on and off the track. That has culminated in two on-track collisions in 2016. ESPN charts the major incidents between the two...

2013 Malaysian Grand Prix

It took Hamilton just two races to claim his first podium for Mercedes. While this race is remembered for Sebastian Vettel ignoring a Red Bull team order to beat Mark Webber, the Mercedes team implemented one of its own, telling the quicker Rosberg to hold station behind Hamilton in fourth place -- the German reluctantly obliged.

The British driver even questioned the radio call and after the race admitted Rosberg had deserved the final spot on the podium. The incident, drowned out in the subsequent days by the "Multi-21" saga at Red Bull, passed by without further controversy as the two friends moved on.

2014 Bahrain Grand Prix

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Equipped with a dominant car in 2014, the Mercedes drivers engaged in a classic wheel-to-wheel duel for the win in Bahrain. A late safety car had seemingly swung the favour to second-place Rosberg, who had the benefit of being on a better tyre, but after the restart Hamilton held firm in a thrilling wheel-to-wheel encounter which passed without the Mercedes cars making contact. In parc ferme after the race the pair engaged in a mock fight, invoking memories of their karting days.

Mercedes was praised in the aftermath for allowing its drivers to race but had benefitted from the tender stage the rivalry was in -- there was no bitterness, no previous flashpoints to speak of and a largely respectful championship unfolding between two men who considered the other to be an old friend.

However, there was more to the race than met the eye. It later emerged Rosberg had used engine modes banned by Mercedes to give himself a power advantage over Hamilton in the closing laps. It was a line crossed, and Hamilton would respond in kind two races later...

2014 Spanish Grand Prix

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Hamilton's fourth win in a row in Spain saw him take the lead of the 2014 title race. To do it he had to hold off a charging Rosberg late in the race, crossing the line just 0.6s ahead of the No.6 Mercedes. Rosberg felt he would have caught and passed Hamilton with one more lap. What Rosberg did not know until he left Spain was that Hamilton only kept him at bay by using the same banned engine modes he had used in Bahrain. Heading to Monaco, the gloves came off.

2014 Monaco Grand Prix

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This one is still controversial. In the closing stages of Q3, both Mercedes drivers started a lap -- Rosberg first, Hamilton second. Rosberg's earlier Q3 attempt had given him provisional pole and then a mistake -- a very odd mistake -- at Mirabeau saw him run deep and into a sliproad, prompting yellow flags and forcing Hamilton to bail out from a lap he thought was already good enough for pole.

Though the stewards cleared Rosberg of any wrongoing, Hamilton was convinced his teammate had intentionally parked his car, saying Mercedes' data backed up his opinion. Hamilton would declare the two were not friends despite their long history. Rosberg went on to convert pole into a win the following day, ending Hamilton's run of four wins. It put the German back in the lead of the championship and prompted a mid-season resurgence.

2014 Hungarian Grand Prix

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Coming to Budapest, Rosberg was leading Hamilton by 14 points in the championship. Pole position, coupled with an engine failure for Hamilton in qualifying, seemed set to give Rosberg an even stronger lead going into the summer break. Hamilton battled back from a pit-lane start before a mid-race safety car shuffled the order, putting Rosberg behind his teammate but on a different strategy.

When Rosberg closed in Mercedes asked Hamilton to move over, knowing the German would have to pit again for fresh tyres. Hamilton refused, reasoning that he had battled through from last position and that he was not prepared to slow down to let Rosberg, his title rival who had started from pole position, through.

Hamilton's decision meant he held on to third, keeping an incensed Rosberg at bay in the final stages after his pit stop. Rosberg went into the summer break seething at the perceived injustice and the lack of punishment for what he considered Hamilton's blatant refusal to be a team player.

2014 Belgian Grand Prix

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Those four weeks of resentment would come back to haunt Rosberg. Trailing Hamilton on the second lap at Spa-Francorchamps, the German attempted a clumsy move around the outside of the Les Combes chicane. The move led to contact, giving Hamilton a puncture and knocking him out of race contention.

Rosberg would recover to finish second behind Daniel Ricciardo but it later emerged the German had left the nose of his car in to "prove a point" to his British teammate by not backing out, the culmination of all his Hungary frustration. Rosberg was punished by Mercedes and booed on the podium. Though he left Spa leading the championship by 29 points the incident would swing the momentum in Hamilton's favour.

After Belgium, Hamilton won six of the remaining seven races to claim his second drivers' championship. Two of those wins involved catching and passing Rosberg on track, at Suzuka and Austin.

2015 Chinese Grand Prix

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Lewis Hamilton's second win of 2015 was faultless but not without controversy. Leading a one-two early in the race ahead of Ferrari -- who had claimed a shock win in Malaysia the race before -- Hamilton was asked to pick up the pace when Rosberg suggested he was backing him into Sebastian Vettel. Rosberg, who finished second, accused Hamilton of compromising his race.

Hamilton was unfazed by the accusation, responding: "It's not my job to look after Nico's race, it's my job to manage the car and bring the car home as healthy and as fast as possible. That's what I did." The win was Hamilton's second of 2015 and he would continue to dominate the opening part of the year, with that season's rivalry lacking the competitiveness of 2014.

2015 U.S. Grand Prix

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Hamilton came to Austin knowing he could win the 2015 title with three races to spare if he claimed victory. After Hamilton very aggressively forced Rosberg wide at Turn 1 to claim the lead, a classic race unfolded where the advantage continuously swung between both Mercedes drivers and the chasing Red Bulls. A fired-up Rosberg led in the closing stages but made a mistake at Turn 12, running deep and letting his teammate through a handful of laps from the flag.

Hamilton never relinquished the lead and claimed his third championship. Rosberg was furious after the race, saying his teammate's Turn 1 move had been "one step too far". He infamously threw a Mercedes cap at Hamilton as they waited to take the podium -- a moment which went viral after the race.

2016 Spanish Grand Prix

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After Austin, Nico Rosberg went on a seven-race winning streak, which included the first four races of 2016. Coming to Spain he led Hamilton by a massive 43 points following a number of issues for the British driver, who then claimed pole position ahead of Rosberg. After a good start for both men, Rosberg passed Hamilton with a great move around the outside of Turn 1.

Coming through the next few corners, Rosberg's car entered an incorrect engine mode due to an switch error the German had made on the formation lap. That meant he was slower than Hamilton coming out of Turn 3, and Hamilton went for the lead. Rosberg closed the door and Hamilton lost control on the grass, eventually spinning into Rosberg and taking both men out of the race.

The stewards deemed it a racing incident and decided Hamilton had been justified in his attempt as he was 17 km/h quicker than Rosberg coming out of Turn 3. Afterwards, Hamilton insisted the incident did not harm his relationship with Rosberg, which he later admitted had mellowed since the bitter days of 2014.

2016 Austrian Grand Prix

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Mercedes' first-lap nightmare in Spain was repeated on the last lap in Austria. Rosberg, struggling with a brake issue, looked on course to record the best win of his career. But in the final laps Hamilton closed in and a mistake from Rosberg at Turn 1 on the last lap gave him better drive on the long run to Turn 2.

Hamilton picked the outside, moving alongside Rosberg as they approached the corner. As Hamilton turned in to make the corner, Rosberg went straight on, causing a collision but damaging the German's front wing. It was another example of Rosberg's no-nonsense attitude, developed over two years of being accused of settling for second best in battles with his teammate, though he claimed Hamilton had simply turned in on his car.

Hamilton would pass the damaged No.6 Silver Arrow to win, while Rosberg would drop to fourth in the final corners. Both drivers blamed the other, while furious team boss Toto Wolff threatened team orders in future races. The stewards blamed Rosberg for the incident, issuing him two penalty points for failing to allow "racing room" and causing a collision.

To be continued...