Bottas was called in as the unscheduled replacement for Nico Rosberg, who quit just days after winning his first F1 world title last year.

Rosberg's decision shocked the sport and sent Mercedes scrambling to find a top talent to partner Lewis Hamilton months after all the driver deals for 2017 had been done.

With Daniel Ricciardo, Max Verstappen, Sebastian Vettel and even Fernando Alonso unavailable, Mercedes effectively bought Bottas out of his contract with Williams.

The thinking was that he had the most untapped potential to challenge Hamilton, who had to be at his brilliant best to keep Rosberg at bay in their dominant Silver Arrows racers.

It's a great opportunity for Bottas to unleash his speed in a front-running car, but also a possible poisoned chalice if he fails to measure up against the triple world champion Englishman.

Bottas, 27, is in the spotlight in his race debut with Mercedes in Sunday's season-opening Australian Grand Prix at Albert Park.

Critics question whether the amiable Finn has the resolve to threaten Hamilton, the accepted benchmark among F1 drivers who is determined to regain the title he lost to Rosberg last year.

In Hamilton's mind, it was misfortune that cost him a title hat-trick last year and he will be determined to crush Bottas quickly to assert his primacy and got for the crown if Mercedes is still the pacesetter.

Bottas accepts he is in the F1 hot seat and being judged in the harsh glare of scrutiny doesn't faze him.

"I think it's a massive opportunity for me," he told Fairfax Media. "The only thing I want to do is win and fight for titles, so now it may be possible. Obviously, we will see, but at least I'm now in a really, really strong team."

From the moment he heard that Rosberg had retired, Bottas set his sights on filling the vacancy, enduring more than a month of protracted negotiations before his release from Williams was secured.

"Well, initially, I was very surprised, like everyone," he said. "But then, yeah, pretty quickly I realised that someone needs to fill the spot and that maybe there would be a small chance I could have an opportunity.

"These kind of opportunities don't normally come along. It's a once-in-a-lifetime thing and, obviously, I was contracted to Williams for this year, but I'm just so pleased that everything worked out and it was possible."

Unlike Rosberg's frosty relationship with Hamilton, which descended into an on-track feud, Bottas believes he can maintain a healthy rivalry - assuming, of course, he can trouble the head-strong Briton, who more than ever regards the Mercedes team as his own.

"He's obviously a really experienced racer and I'm sure he understands that as teammates, we want to be better each other," Bottas said. "That's how it always goes. You always want to be better than your teammate and I hope we can keep it professional like that and I think it's possible.

"I've experienced a good teammate relationship with Felipe Massa at Williams. It was exactly like that. We were racing hard on the track, but then outside of the track, you know, we would kind of leave it there and just acknowledge the fact that that's racing.

"And I'm sure Lewis can understand that as well and I see no reason why we shouldn't be able to work well as a team."

Australian star Daniel Ricciardo is in a similar position of potential conflict with his precious 19-year-old Red Bull Racing teammate Max Verstappen, F1's fast-rising phenomenon.

Bottas rates Ricciardo highly, but expects him to have to fight hard to fend off the fearless young Dutchman.

"Daniel is a great driver," he said. "I raced against him already in junior formulae and it's nice to be racing him in F1.

"But I think they're both great drivers. Max, obviously, very young and talented, Daniel more experienced. I think they're going to be close again in terms of how quick they are.

"Definitely, at some point of the season, they're going to be really strong. But if you ask me personally, I'm expecting a close fight between Daniel and Max."