It remains one of the most fractious team-mate partnerships of recent times and provided the defining rivalry of Formula 1 in the 2010s. Lewis Hamilton versus Nico Rosberg, the two old karting friends-turned bitter combatants for glory in the first three seasons of the turbo hybrid era, provided a compelling focal point for F1 at a time when a lack of opposition from Ferrari and Red Bull meant the Silver Arrows went into almost every weekend expecting to win.
But the enmity that developed between the pair - with flash-points at Monaco and Spa in 2014, then most memorably of all at Barcelona in 2016, allowing Max Verstappen to score his first win - only pushed both onto greater heights.
When Rosberg retired at the end of 2016, having clinched the world title at a tense Abu Dhabi finale, there was a sense that a great weight had been lifted from Hamilton's shoulders. With Valtteri Bottas joining from Williams to fill the berth, there was a clear hierarchy in the team - even if Toto Wolff would never admit as much - and Hamilton could get on with the business of seeing off a renewed challenge from Ferrari and Sebastian Vettel without having to worry about mind games from within his own camp.