Lewis Hamilton's teammate Valtteri Bottas has been a diligent number two driver for years now, but an incident at last weekend's Spanish Grand Prix will be giving Mercedes flashbacks to days when things were not so easy to manage.
Over the course of his long and illustrious career in Formula 1, Hamilton has never had a teammate that got under his skin quite like Nico Rosberg did during their time together at Mercedes.
The Hamilton-Rosberg days
Hamilton arrived at the Silver Arrows in 2013 to replace Michael Schumacher, with Rosberg entering his fourth year at the team. It was Rosberg's domain, but Hamilton was a world champion and a 20-time race winner, compared to Rosberg's single triumph in China in 2012.
— Mercedes-AMG PETRONAS F1 Team (@MercedesAMGF1) March 17, 2015
The two were friends from their karting days, but when Mercedes became dominant in 2014, the gloves came off. There were incidents throughout the year, with the tensions reaching their peak in Belgium when the two teammates tagged each other, ruining Hamilton's race and handing the race win to Red Bull.
Hamilton and Rosberg received a talking to, and it was clear the following year that things had changed. Hamilton won the championship in both 2014 and 2015, and the Nico Rosberg that appeared in 2016 was different. He attacked Hamilton in a way no teammate had done before, and ultimately won the championship that year.
It was an incident at the start of that year, though, that changed the way Mercedes managed their drivers. At the 2016 Spanish Grand Prix, five years ago today, Hamilton and Rosberg collided on the opening lap, taking each other out of the race and handing a debut win to Max Verstappen.
The crash was the defining moment of the 2016 season, and was followed by another collision on the final lap of the Austrian Grand Prix, which turned a 1-2 finish into a 1-4 finish for Mercedes.
Less than a week after clinching the 2016 title, Rosberg announced his shock retirement from the sport at the age of just 31.
It had been a bitter and gruelling battle for the title, that had taken its toll on the team. Luckily for Mercedes, their car was utterly dominant, otherwise the constant battling between the two could have cost the team the championship.
The Hamilton-Bottas era
When it came to choosing Rosberg's replacement, Mercedes opted for Williams driver Valtteri Bottas for 2017, and he has remained at the team ever since. It's become clear in the years since that Bottas is at Mercedes to serve a function: win the constructors' championship.
The team have learned their lesson from the Hamilton-Rosberg days. Having the best car is a near guarantee of a constructors' championship, but if your two drivers are constantly racing each other, you run the risk of throwing away points if they collide or hold each other up.
In their time together at Mercedes, Bottas has won nine races. Hamilton has won 45 in the same time period. To look at those numbers, you'd think that Hamilton has been on another planet to Bottas - and it is true, there has arguably never been a more complete driver than the Briton.
But Bottas has also been diligent in playing the "number two" role as Hamilton's teammate.
In Germany 2018 he agreed not to challenge Hamilton for the lead. That same year, he gave up a win in Russia to help Hamilton in his title battle against Ferrari's Sebastian Vettel. Hamilton being so far ahead of his teammate has put him in the ascendancy, and it's meant that Bottas has regularly been required to play second fiddle.
It has led to public tension - after winning the 2019 Australian Grand Prix, Bottas proclaimed, "to whom it may concern, fuck you" - a not so subtle nod to those who doubted his conviction in racing his teammate. He also publicly snapped at his team boss Toto Wolff for calling him a "wingman" to Hamilton's 2018 title bid.
But, in last weekend's Spanish Grand Prix, there was a glimpse that Bottas may not be happy to continue in that role. With Hamilton on a charge and chasing down Red Bull's Max Verstappen for the race win, Bottas was asked to let his teammate through. It made sense - Bottas was on older tires, Hamilton was faster, and the Spanish track is notoriously hard to overtake on. It was the sensible call from the team, regardless of the title situation.
Bottas was slow to let Hamilton through though, and Hamilton ultimately had to dive down the inside of turn 10 to make a genuine overtake. Purists will say that this was what F1 should be, fighting for each position - and they would have a point - but from a Mercedes standpoint it will surely have raised a few eyebrows.
Other than Sebastian Vettel's early charges in 2017 and 2018, Mercedes have not had to fight another team for the drivers' championship since the current turbo hybrid engines were introduced in 2014 - this year is different.
Max Verstappen in the Red Bull car has a lot of pace, and it looks like there will be a season-long title fight between himself and Hamilton. If Mercedes are to clinch an eighth consecutive double championship win, they will need Bottas to play his role diligently, otherwise they will be looking at alternatives for next year.
Pundits like former Renault driver Jolyon Palmer have suggested that Hamilton's eventual win in Spain saved Mercedes from some difficult conversations. If Bottas had held up his teammate and ultimately cost the team the win, there would surely have been serious consequences.
It certainly seems as though Hamilton is Mercedes' sole contender for the drivers' championship this year, as he has been every year since Bottas' arrival. What will be fascinating from here on in is just how willing the Finn is to continue playing "wingman" to his teammate.
Interesting times are ahead at Mercedes...