The 2011 Canadian Grand Prix is one of modern Formula 1's most famous races, with Jenson Button's winning after a last-lap pass on Sebastian Vettel. But was the Brit's last-to-first victory a wet-weather masterclass - or just lucky?
When counting down the greatest races in recent Formula 1 history, the chaotic Canadian Grand Prix is a regular fixture in any top-10 list.
Remembered for being the longest race F1 race ever at four hours, four minutes and 39 seconds, it was where Jenson Button took a remarkable victory on the final lap.
Fighting back from six visits to the pits, a collision with his team-mate and running last with 30 laps to go, it is often hailed as the finest win of his F1 career. Button himself called it "my greatest race" in his 2019 book, How To Be An F1 Driver.
But when it came to look back on Canada 2011 ahead of the latest F1 Rewind live stream this weekend, one day after the ninth anniversary of the race, there was an interesting counter point to that.
In a 2016 feature ranking the 10 greatest races of Button's F1 career, Autosport editor Kevin Turner did not place Canada 2011 highly. In fact, he didn't place it at all, only featuring in the 'honourable mentions' section at the end.
"Surprised this isn't on the main list? It's Button's most famous success, but this required a bit more luck than some of the others," Turner wrote.
While it was a victory of a different ilk to his victories at Hungary in 2006 and 2011 (third and second respectively on the list) or his defeat of McLaren team-mate Lewis Hamilton at the 2010 Chinese Grand Prix (#1), it required plenty of guile and composure to rise up the order.
And yes, some big slices of luck.
The opening 40 laps of the race took three hours and 20 minutes to complete, and offered just 12 laps of green flag running. Torrential rain in the lead-up to the start meant the race started behind the safety car, which made two further appearances before the red flag came out on lap 25, sparking a two-hour delay.
"I saw some footage of Ron [Dennis]. He was just there in the garage, his face is lifeless. He's got one car out, one car that has pitted five times and is last. I don't think he was in the best mood!" Jenson Button
Button had started the race seventh for McLaren, but gained a place when the race went green on lap five after Hamilton spun Red Bull's Mark Webber around, sending him to the rear of the field. A mistake from Button at the Turn 6/7 chicane - later the site of his race-winning pass - allowed the Mercedes of Michael Schumacher to get by and Hamilton regained a position, leaving the McLarens nose-to-tail as they judged the limits of grip in the damp.
Button and Hamilton clashed on lap seven, after Schumacher had forced a gaining Hamilton wide at the hairpin on the previous lap. Hamilton tucked into Button's slipstream as they came across the main straight, following his team-mate as he drifted toward the pit wall. Hamilton pulled out to pass, only for an unsighted Button to squeeze him, causing a collision.
"Suddenly the car went sideways, and I initially didn't realise what had happened," Button said on Sky F1 last year. "I thought I'd had a puncture or something or a failure. But what had happened was Lewis was on my left, we touched, he went into the wall and I pretty much went into the wall as well.
"It's never a good feeling as a driver, with anyone, but especially your team-mate. I think I said on the radio: 'What is he doing!?' I don't know why I said that, it was just heat of the moment, trying to put the blame elsewhere rather than on me!"
The incident forced Button to make his first visit to the pits after limping around the lap with a puncture, switching to intermediate tyres at the same time. It dropped him some 30-seconds behind leader Sebastian Vettel, with that gap then reducing thanks to the safety car called to allow Hamilton's now stopped car to be recovered.
Button avoided a penalty for the clash, but had been caught speeding under yellow flags, resulting in a drive-through. He could not serve this under the safety car, making his earliest opportunity the first lap after the race resumed. He dropped from 12th to 15th as a result, the gap to Vettel returning to 20 seconds. The intermediates briefly looked like the right tyre to be on, allowing him to claw through to eighth before admitting defeat and pitting for a third time on lap 19 to switch back to wets. The safety car was called one lap later, leaving Button 10th under the red flag.
He used the stoppage to find Hamilton to apologise for causing his retirement.
"I went to go and say I was really sorry about the incident," Button later explained. "He said 'I get it, you didn't see me, I don't put blame on you.' It was a great chat with Lewis, because it meant I could focus on getting my head back in the game, getting ready for the restart."
But another incident would quickly follow. After a fourth stop to switch from wets back to intermediates just one lap after the race returned to green, Button got caught up in a clash with Fernando Alonso at the first chicane.
"I dived down the inside of Fernando into Turn 3, and we both tried to go through the corner side-by-side, which you just can't do there," Button said. "He really didn't want to give up the place, I really didn't want to either, and we touched wheels, he spun around and got beached on the kerb. I picked up a puncture and front wing damage, so I had to crawl back to the pits."
This dropped Button to last place, over one minute and 40 seconds behind Vettel - but the gap was again wiped away by the safety car called to allow Alonso's Ferrari to be recovered.
"I saw some footage of Ron [Dennis]," Button remembered. "He was just there in the garage, his face is lifeless. He's got one car out, one car that has pitted five times and is last. I don't think he was in the best mood!"
So from there, the only way was up. As the rain halted and the track started to dry, Button began to pick up position after position. He was aided by some drivers being forced to pit again after gambling on full wets in the hope of more rain arriving, but within 10 laps of the race restarting, he had already clawed his way back to P10.
Button was then one of the first drivers to make the switch to slick tyres thanks to the drying line, pitting two laps earlier than leader Vettel. Passes on Nick Heidfeld and Kamui Kobayashi meant that with 15 laps to go, Button sat an impressive fourth, the gap to Vettel falling from 47 seconds to just 15 thanks to the Red Bull's final stop.
"In a 70-lap race, I led half a lap. I crossed the line, and I'd never seen my team so excited" Jenson Button
Vettel was able to respond to Button's pace, but was then dealt a blow when the safety car was called following a crash for Heidfeld that left debris strewn across the track. It also left Button fourth on the road, fifth in the train thanks to the interloping Timo Glock, but after passing the Virgin car he set his sights on Schumacher and Webber ahead.
Webber's mistake with seven laps to go gave Button a run coming out of the last chicane, the Briton avoiding a bold defensive move as the Australian regained control of his car. Button caught the snap and kept his foot down to take third, before picking off Schumacher one lap later. Button had five laps to catch and pass Vettel, and was going considerably quicker.
"Did I think I could win it? Probably not," conceded Button. But his engineer was having none of it. "We can have him, we can win this race, Jenson!" came the message from Dave Robson, geeing his driver up.
Button continued to draw Vettel in as the laps ticked down, noticing a lock-up at Turn 1 from the Red Bull driver as they started the final lap. It left Button plotting his move for the lead: "If we get to the end of this lap, and we get DRS into that last chicane, it's all or nothing - I'm gonna dive down the inside."
But he didn't have to. As Vettel turned in at Turn 6, his erstwhile-trusty RB7 slithered to the outside of the corner, its rear jutting out. It opened the door for Button to move into the lead with half a lap to go.
"I saw this Red Bull going sideways," Button said. "I was gobsmacked. I just held my breath and stared at him as I drove past. In a 70-lap race, I led half a lap. I crossed the line, and I'd never seen my team so excited."
It capped off a sensational last-to-first hunt for glory from Button, giving the chaotic race the ending it deserved.
So after all of that, what is the case for luck being the deciding factor in Button's win?
The safety cars certainly helped, one of which he inadvertently caused himself by biffing Alonso off the track. The fact he avoided a penalty for either clash, both put down as a "racing incidents", was also fortunate. The safety car periods saved Button more than two minutes in total.
And there were mistakes. The clashes with Alonso and Hamilton meant it could hardly be remembered as a super-clean race. Vettel, by comparison, made just a single error, coming at the very end.
But Button's real magic started as the rain stopped. From then on, he hardly put a foot wrong, proving his skills in greasy conditions and making the tyre calls at exactly the right moments.
It may have lacked the dominance of some of his other wins, and it may have been lucky in places, but Canada 2011 brought out the characteristics that we most fondly remember from Button's F1 career.
His most complete win? Perhaps not. But the win most fitting of Button's rollercoaster F1 career? Without a shadow of a doubt.
Get unlimited access to the world’s best motorsport journalism with Autosport Plus