F1 2021 produced a titanic title battle between Red Bull's Max Verstappen and Mercedes' Lewis Hamilton.
With the pair going head-to-head week in and week out, here are the 10 most dramatic moments from their duels over the course of the season.
Do you agree with our list? Let us know what moments you would have included, or which ones you believe shouldn't be on the list...
Hamilton slides off at Imola
Following on from a contentious ending to the season-opener in Bahrain, Imola saw Lewis Hamilton and Max Verstappen go wheel-to-wheel once again.
Verstappen, starting from third on the grid, got a great launch off the line to pull alongside Hamilton into the first corner - Verstappen winning out as he pushed Hamilton wide onto the sausage kerbs.
The first half of the race saw Verstappen open up a small lead over Hamilton before the opening round of stops, with Hamilton fighting back after the tyre changes. Attempting to close up on Verstappen, Hamilton made a small error at the Tosa corner as he was lapping Williams' George Russell.
Sliding off into the gravel, Hamilton attempted to power his way out of the problem but, annoyingly for him, the car held grip and propelled him straight into the barrier and damaged his front wing.
Hamilton managed to gently reverse himself out of the gravel and rejoin, but was a lap down by the time he pitted for repairs and resumed.
However, moments later, the race was red-flagged as Valtteri Bottas and Russell collided on the run down to Tamburello. This allowed Hamilton to resume the race from eighth place, and he worked his way back up to second by the chequered flag to minimise the damage.
Verstappen crashes out of the lead in Azerbaijan
Verstappen was comfortably in control on the streets of Baku, after working his way up into the lead from a third-place grid slot.
With Aston Martin's Lance Stroll having a rear tyre failure through the final sector, Verstappen suffered a similar failure shortly after as he approached the start/finish line to begin Lap 47 of 51. The race was immediately red-flagged, as he radioed in to shout, "F**king tyre!"
With just five laps to go, and enjoying a five-second lead over teammate Sergio Perez to set up a Red Bull 1-2, Verstappen's certain win went begging as a result of the failure.
Worse for Red Bull was the fact that Hamilton hooked up the restart to take the lead, only to sail straight off into the escape area and tumble down the order. He had left his 'brake magic' on as he approached the braking point, with this being a setting specifically for warming the brakes in non-racing scenarios.
The mistake cost Hamilton any chance of points, with Azerbaijan giving Perez his first win as a Red Bull driver and the two title rivals left the city empty-handed.
The battle becomes a war at Silverstone
Silverstone proved to be the first major flashpoint between the two title protagonists, as they lined up on the front row for the Grand Prix.
With the British Grand Prix playing host to the first Sprint Qualifying weekend, Hamilton was shocked to be beaten in the short race after taking pole position on the Friday evening.
Hamilton threw everything at Verstappen on the opening lap of the Grand Prix, with the Dutchman resisting his advances into Brooklands but compromising his exit from Woodcote. This allowed Hamilton to get a run on him into Copse, with the Mercedes driver keeping his nose up the inside as Verstappen swooped to take the corner.
Despite Verstappen appearing to leave enough room, the pair collided and the Red Bull flew off into the barriers at high speed. Verstappen was battered and bruised from the 51G impact, being taken to the hospital nearby for precautionary checks as a result.
With the race red-flagged, Hamilton was able to get the damage to his car repaired and resume the race. After serving a 10-second time penalty for the collision, he hunted down the leading Charles Leclerc and passed to pick up the win and gain a massive 26 points back on Verstappen.
This event escalated the bad blood that had been brewing between the rival teams, with Red Bull unhappy with Mercedes' displays of joy at what they regarded was a hollow victory. Mercedes and Hamilton, by contrast, felt they had done little wrong and, given that Verstappen was uninjured, their celebrations at winning Hamilton's home race were justified.
Bottas goes bowling in Hungary
Having picked himself up after the troubles of Silverstone, Verstappen headed to Hungary eager for a refresh ahead of the summer break.
At a wet and gloomy Budapest, Verstappen lined up in third place behind the two Mercedes drivers but made a good start to slot in behind Hamilton into Turn 1.
Bottas, having been beaten off the line by the Red Bull and Lando Norris' McLaren, fell in directly behind Norris but misjudged his braking. Slamming into the back of Norris, the British driver was powerless to stop himself barrelling into the side of Verstappen's Red Bull. Bottas, in turn, ploughed into Perez, knocking out the second Red Bull on the spot.
The chaos also included a secondary crash further back, with Lance Stroll taking out Charles Leclerc and Daniel Ricciardo.
The resulting red flag allowed Red Bull to make some rudimentary repairs to Verstappen's car, and he fought back to finish in ninth - two crucial points towards his World Championship campaign.
Russell's remarkable front row
Qualifying in the rain at Spa-Francorchamps is guaranteed to be spectacular, but nobody thought they would see a Williams on the front row of the grid.
Following Norris' big crash in qualifying, the 10 drivers who progressed to Q3 had to put everything on the line.
A clever tyre warm-up strategy from Williams saw Russell provisionally go to pole position during the closing stages of qualifying as the British driver executed a stunning lap.
Hamilton couldn't go faster, but Verstappen snatched top spot in the dying seconds to prevent a massive upset.
Nevertheless, Russell's Q3 effort was one of those moments you couldn't quite believe was happening and it was further rewarded with a podium due to the shortened race 24 hours later.
Hamilton and Verstappen collide again!
Heading to Monza, and the second of the Sprint Qualifying weekends, Hamilton was eager to strike back after Verstappen's controlling drive in the Netherlands.
Mercedes locked out the front row on Friday evening, but Hamilton fluffed the start of the Sprint Qualifying race on Saturday. This allowed Verstappen to settle into second place and guarantee a front-row start for the Grand Prix.
Starting the race, Verstappen settled into second as Hamilton set about climbing from fifth place. A slow stop for Verstappen on Lap 23/53 looked as though it had handed the initiative back to Hamilton, but Hamilton's own slow stop meant he and Verstappen were side-by-side going into the first chicane on Lap 25.
Verstappen went around the outside of the right-hander, staying on the inside for the left-hander immediately after. But Hamilton held his line, forcing Verstappen to clamber over the kerbs. These pitched his car into the air, with the Red Bull coming to land on top of the Mercedes.
Thankfully, Hamilton's Halo device prevented him from suffering any injuries as the rear tyre of the Red Bull scraped across his helmet, and the pair conspicuously didn't approach each other as they clambered from their stricken cars to begin the long walk back to the pits.
Verstappen was later given a three-place grid penalty for the incident.
Norris took a maiden pole position with a superb lap in mixed conditions at the Russian GP, and he was set to win his first F1 race until rain turned the Grand Prix on its head.
Norris faced big pressure from Hamilton in the second half of the race, but held his own.
However, the weather gods had something to say as rain began to fall with five laps to go. Hamilton opted to pit for Intermediates, having ignored the first call to pit, whilst Norris wanted to brave the rain out.
It wasn't clear who was right, until Norris arrived at the end of the first sector with three laps to go when the rain was pouring. He had no grip and slid off the track, conceding the lead to Hamilton and being forced to limp back to the pit lane to eventually switch tyres as he lost the win.
Norris' heartbreak gave Hamilton his 100th victory in F1, whilst Verstappen made the most of the rain by snatching a surprise second place - having started from the back of the grid after an engine change.
A heated battle in Brazil
The Brazilian GP weekend might just get the reward for the craziest event of the year. First, Hamilton was excluded from qualifying for an illegal opening in his rear wing when using DRS.
At the end of the same session, Verstappen was fined €50,000 for touching Hamilton's rear wing in parc ferme. To add to the tension, both decisions were announced just before Sprint Qualifying.
From the back of the grid, Hamilton impressively finished in fifth. However, he had to serve a five-grid place penalty for a new Internal Combustion Engine, so he started the race from 10th.
Hamilton quickly made his way through the field and was in pursuit of race-leader Verstappen.
The Mercedes man appeared to get by at Turn 4 in the closing stages of the race, but Verstappen threw his car into the corner to retain the lead as both drivers went off the track. To the anger of Mercedes, the move was not punished.
Hamilton managed to get the job done on the track, cruising by on the run down to Turn 4 and covering the inside to ensure that Verstappen couldn't make a similar move.
Chaos in Saudi Arabia
The battle between Hamilton and Verstappen continued in Jeddah with a huge scrap.
A red flag gave Verstappen a huge slice of luck to take the lead, having been stuck behind Bottas in third.
But Hamilton got the jump on the first standing start restart and was momentarily back in front. Verstappen had other ideas as he went around the outside, jumping over the kerb at Turn 2 to get back ahead as Esteban Ocon slipped past Hamilton.
Behind, a big accident involving Perez, Russell and Nikita Mazepin caused another red flag.
The drama carried on as Race Director Michael Masi negotiated how the grid should be formed with Red Bull and Mercedes, due to Verstappen's aggressive actions on the initial restart.
Verstappen was demoted to third, with Hamilton and Ocon in front. Now on the Medium tyres, Verstappen dived down the inside at Turn 1 on the second standing start restart to snatch the lead. It was a bold, brave overtake from the Dutchman. Once Hamilton got by Ocon, he was on the chase once again.
Just like Brazil, Verstappen didn't make things easy. He cut the first chicane to keep the lead following Hamilton's first attack and was ordered to give the place back, strategically.
Hamilton didn't know Verstappen was giving up the lead, so ran into the back of him in a bizarre incident.
Verstappen pushed on, but then let Hamilton by again, only to immediately go up the inside at the last corner and repass his rival.
Finally, Hamilton got by with an aggressive overtake as he held Verstappen wide at the final turn. It was a confusing, wild rollercoaster of a race in Saudi Arabia.
The most dramatic end to any season
Hamilton was on course to win a record eighth title with a dominant victory in Abu Dhabi, but a late Safety Car caused by Nicholas Latifi added one final twist to this epic season.
There was huge controversy surrounding the Safety Car procedure as only some cars were allowed to unlap themselves. Ultimately, it set up a grandstand finish with Verstappen on fresh Soft tyres, versus Hamilton on old, Hard rubber.
Verstappen took the first opportunity to go for it by diving up the inside at Turn 5, taking the lead.
Hamilton tried to fight back down the next two straights and was able to get alongside, but Verstappen sealed the move and the title by fending him off at Turn 9.
It was simply an unbelievable finish and there may never be scenes like that ever again in F1.
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