Formula 1 in 2021 will be remembered forever as Max Verstappen and Lewis Hamilton fought each other for the title in one of the most intense seasons the sport has seen.
It wasn't the only battle this year, though, as the teammate head-to-heads across the grid raised eyebrows throughout the season.
Let's take a look at who has come out on top at each team after 22 thrilling races.
Mercedes: Lewis Hamilton vs Valtteri Bottas
Head-to-head: 18 - 4
Points: 387.5 - 226
Lewis Hamilton comfortably beat Valtteri Bottas for a fifth consecutive season, picking up eight wins on the way.
Bottas simply didn't have the same ability to extract the performance from his tyres over a race stint compared to Hamilton, and was rarely a factor in the battle for the victory at each Grand Prix.
Red Bull: Max Verstappen vs Sergio Perez
Head-to-head: 19 - 3
Points: 395.5 - 190
New World Champion Max Verstappen scored more than double Sergio Perez's points haul during the 2021 season.
It was widely expected, with Perez never beating Verstappen all year when both drivers finished the race. Don't be surprised if that streak continues into 2022.
Ferrari: Charles Leclerc vs Carlos Sainz
Head-to-head: 14 - 8
Points: 159 - 164.5
Charles Leclerc beat Carlos Sainz 14 times in 2021, but finished behind the Spaniard in the Drivers' Championship.
That's because Sainz made the most of some fortune and mistakes from others to stand on the podium four times, which boosted his points haul.
McLaren: Lando Norris vs Daniel Ricciardo
Head-to-head: 15 - 7
Points: 160 - 115
Lando Norris had a brilliant year, beating teammate Daniel Ricciardo for the majority of the season.
Norris improved his tyre management skills significantly, whilst Ricciardo often struggled in the midfield due to his poor starting positions. This was arguably the biggest inter-team surprise of the year.
Alpine: Fernando Alonso vs Esteban Ocon
Head-to-head: 11 - 10
Points: 81 - 74
The stats tell the story at Alpine as Fernando Alonso edged out Esteban Ocon by the slimmest of margins.
Despite Ocon's 25 points in Budapest, for winning his maiden Grand Prix, Alonso was the more consistent driver in 2021.
AlphaTauri: Pierre Gasly vs Yuki Tsunoda
Head-to-head: 16 - 5
Points: 110 - 32
Pierre Gasly dominated his rookie teammate Yuki Tsunoda, fighting at the front of the midfield whilst Tsunoda was battling towards the back of the mid-pack.
Gasly is another driver who's vastly improved his tyre management in F1, whilst Tsunoda still has to get to grips with the Pirelli rubber. There will be a reset next year, though, when the new 18-inch tyres are introduced.
Aston Martin: Sebastian Vettel vs Lance Stroll
Head-to-head: 10 - 11
Points: 43 - 34
Arguably the most inconsistent driver pairing in 2021 were Sebastian Vettel and Lance Stroll, and this is reflected in their head-to-head.
Vettel was the stronger driver on the whole, but misfortune meant Stroll was able to match him on the stats cards.
Williams: George Russell vs Nicholas Latifi
Head-to-head: 15 - 5
Points: 16 - 7
Whilst George Russell dominated Nicholas Latifi in qualifying, the Canadian was more of a match in terms of race pace.
The pair maximised their chances of scoring points to earn Williams eighth in the Constructors' Championship, and Russell's better qualifying meant he often stayed ahead in the Grand Prix.
Alfa Romeo: Kimi Raikkonen vs Antonio Giovinazzi
Head-to-head: 10 - 10
Points: 7 - 3
Kimi Raikkonen had the better race pace than Antonio Giovinazzi for most of 2021, using his experience to get the most out of the Pirelli rubber.
Raikkonen sat out two races, due to a positive coronavirus test, where he missed out on an opportunity to beat Giovinazzi. Although it can be argued that he may have been beaten himself at those races.
Haas: Mick Schumacher vs Nikita Mazepin
Head-to-head: 16 - 6
Points: 0 - 0
Mick Schumacher was only beaten three times by Nikita Mazepin when both drivers saw the chequered flag.
The head-to-head doesn't show the big advantage Schumacher had at some races, where he generally finished more than one pit-stop ahead of Mazepin.
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