Melbourne - Valtteri Bottas says something changed "inside his head" after being overshadowed by team-mate Lewis Hamilton last year, with the fired-up Finn unloading on his critics after winning the Australian Grand Prix.
The 29-year-old Mercedes ace, hampered by mechanical problems and bad luck, failed to win a single race in 2018 as the Briton stormed to 11 victories and secured a fifth world title.
It sparked criticism of his abilities, which clearly irked Bottas who let rip on the team radio after crossing the finish line in Melbourne for his first chequered flag since Abu Dhabi in 2017.
"To whom it may concern, fuck you," he said after beating Hamilton by almost 21 seconds, with the nearest Ferrari of Sebastian Vettel 57 seconds adrift.
He explained later that the comment was inspired by the non-believers, who he wouldn't identity but that "it would be quite a long list".
"It just came, I just wanted to send my best regards," he told reporters. "That's it. Honestly, I didn't think about it or plan it, it just came.
"Obviously there are many people who support you, and honestly I appreciate that a lot. There are many people around me, supporting me.
"There are always ups and downs, and you can really see the true support quite easily. And then through the difficult times there's the other part, which is a lot more negative."
Bottas, conscious that he needs to deliver this year with promising Frenchman Esteban Ocon waiting in the wings as the team's reserve driver, said he learned a lot from 2018 and had taken it on board.
"For sure every year you learn as a person, you learn about yourself, what works for you, what doesn't work for you in terms of preparation," he said.
"How you rest, how you spend your free time, how you do the training, how much training, what kind, all those kind of things, travel plans, all sorts.
"So (I'm) just trying to optimise everything for this year, try to maximise every single thing that is possible.
"I don't know, it's quite difficult to explain what's been going on here last winter, inside of my head, and definitely something changed in terms of the way I feel about things in life in general and in racing."
While Bottas drew first blood against Hamilton and Ferrari, there is a long season ahead with another 20 races to go before the world champion is crowded.
Hamilton, who was left mystified by his lack of speed after dominating the free practice sessions and qualifying, was left ruing a wheelspin at the start that let Bottas take the lead at the first corner.
"Ultimately I didn't do a good enough job," he said.
Reports suggested Mercedes had discovered damage to the floor of his car, possibly caused by hitting debris or running across a kerb, which would explain why he couldn't keep pace with the Finn.
Despite his disappointment, Hamilton said he was happy for Bottas and would bounce back at the next race in Bahrain.
"Valtteri drove an incredible race so he truly deserved it and we just have some work to do," he said.
"But it's still a great start to the year and more than we could have hoped as a team."
For pre-season favourites Ferrari it was a rude wake-up call, with the Italian team blaming balance setup issues for their lack of a competitive edge.
"We were just slow," said Vettel. "We need to get back, have a good look and I'm sure we'll find something because we know that the car is better than what we have seen today."