Former F1 driver Jolyon Palmer, who left Renault during the 2017 season, is part of the BBC team and offers insight and analysis from the point of view of the competitors
What a difference a year makes.
In 2018, Valtteri Bottas left Melbourne after the opening race of the season on the back foot.
He had a big crash in qualifying, started well down the grid, and just about managed to salvage a few points with eighth place. His team-mate Lewis Hamilton took pole by more than half a second and only lost the win due to a Mercedes strategy error.
Fast forward 12 months, and Bottas has sent a convincing message of intent for the remaining 20 grands prix with a resounding victory.
And he finished the race with a defiant message to those who criticised his lacklustre performances in the second half of last year.
"To whom it may concern," he said over the radio on the slowing down lap. "F*** you."
It was wild and cutting in equal measure from the usually calm Finn, and it will resonate for much longer than the week and a half before the next race in Bahrain.
What went wrong in 2018
Last season was a really torrid time for Bottas. He took no wins and managed only fifth in the championship in a car in which Hamilton scored 11 victories and tied up the title with two races still to go.
His first half of the season was decent - but unlucky. He could have had a couple of wins had his luck been better and by the summer Bottas had the security of a new contract for 2019 in his pocket.
Had Mercedes waited to offer that contract to him, one wonders whether Bottas would be in this Mercedes seat at all right now because Esteban Ocon remains without a drive. The Frenchman was in Melbourne looking on as Mercedes reserve, because his chances of a new contract died last summer - after Bottas had signed his new deal.
Ocon is extremely talented and seen as a potential future champion for the Silver Arrows. Given the way Bottas tailed off in such an extreme fashion at the end of 2018, had the second seat still be undecided, Mercedes might have been tempted to remove Bottas after only his second season with the team.
How Bottas bounced back
- Valtteri Bottas' Australian GP win 'makes new F1 season interesting'
- Podcast: Australian Grand Prix Review
Right now, it seems a good thing that Bottas is still around in Mercedes. He has had a long, soul-searching winter and come back a visibly different man than he was 12 months ago.
Bottas has much more edge to him than I've ever seen in his career. He has always been a quick, talented driver, that's why Mercedes F1 boss Toto Wolff picked him straight out of GP3 for a seat at Williams back in 2013 and then gave him the big drive at Mercedes once Nico Rosberg retired at the end of 2016.
What he has lacked until now, though, is that last bit of fight that champions must have.
I said last year that he was seen as something of a soft touch, and that was epitomised with the way he fell into - and accepted - his wing-man role for Mercedes, helping Hamilton to the title, giving up a grand prix victory in Russia in the process.
But this year is a fresh start and Bottas seems intent on not having a repeat of that situation by the time we get to the summer again.
Hamilton is now a five-time world champion, while Bottas has won just four races and is generally regarded as a number two to Hamilton.
But 2019 is a new season, both drivers started from zero points again and as such they are free to race.
The shackles that prevented Bottas from winning a race in 2018 are no longer there, and the only way they are going back on is if he falls too far behind Hamilton in the title race again.
Throughout the weekend in Australia, Bottas was closer on pace to Hamilton than he was through most of 2018, almost pipping him to pole until the Brit's last-gasp attempt.
But for Bottas to end up just 0.1 seconds behind is still a great effort, when you take into account the fact that Hamilton has had every pole position in Melbourne since 2014 - he clearly clicks with the circuit.
Hamilton has a total of eight career poles at Albert Park, but he has won the race only twice, and this year it was his team-mate who beat him to the win.
The last time Hamilton was beaten by a team-mate in Melbourne it was by Nico Rosberg in 2016. The parallels are interesting.
Then as now, Hamilton qualified on pole, but Rosberg beat him into Turn One and won the race under minimal pressure. Twenty races later, the German was celebrating a first world title - albeit partially thanks to a hefty dose of bad luck with reliability for Hamilton.
Like Rosberg's in 2016, Bottas' Melbourne victory was easy in the end.
Hamilton drifted off after his pit stop, had a very uncharacteristically erratic and slow pace compared to Bottas, and limped home in a distant second. Floor damage found after the race might explain this in part, but doesn't take away from Bottas' dominance on Sunday.
Can Bottas go all the way?
It's far too early to declare Bottas to be a 2019 champion-elect, or even to be in the title fight but nobody would have given him a chance of it a week ago, and there are encouraging signs, other than the obvious fact that he won the race.
Bottas appears to have an edge to him this year - and the sweary radio message was just final confirmation.
Physically, he looks like he has taken advantage of the driver weight limit going up and put on some muscle mass, bulking out slightly. He's also supporting new facial hair which ensures that, physically as well as psychologically, he appears more rugged than the 2018 Bottas.
Off track, he looked upbeat and chirpy in the paddock throughout the weekend, and on it he was clinical. The fact that he was desperate to take fastest lap says a lot.
If I was in his position, leading the race comfortably, having not won in over a year, I'd have been happy to turn down the engine and bring it home, taking the 25 points and getting a monkey off my back.
Not winning a race as a Mercedes driver gives the media and everybody else an easy chunk of criticism to throw, which he could just simply have put an end to.
The team were clearly in my way of thinking, telling him that they weren't happy taking any chances.
The fact Bottas declared on the radio that he didn't care and he was going for it either way was one thing, but then to smash in the fastest lap on the penultimate tour, by a healthy half-second margin, showed he wasn't just all bark over the radio.
There was some bite behind it and under the new rules this season it earned him an extra point and the maximum 26 for the day.
Finally, there was his celebration - wild and cutting in equal measure. The elation from the usually calm Finn was good to hear and see.
Bottas has fired a shot back at his critics. Not only was he aware of them - as most drivers are, even though they will put on a tough exterior and claim not to pay any attention to the media - but he rose to the challenge and hit back, with one of the most dominant wins seen for a while.
You can be confident Hamilton will bounce back in Bahrain - he's usually so good when his back's against the wall, and Ferrari will be wanting to silence their critics with a strong display following their lacklustre weekend.
There are 20 races to go, the true pecking order hasn't even begun to show itself on a Melbourne circuit that is unique and unpredictable in equal measure.
But one thing is clear - Bottas' wingman days are over for now. He's in the 2019 season to win.