LONDON • Lewis Hamilton has rarely avoided publicity and shares his life away from the track openly with his millions of fans on Twitter. His new team-mate takes a more sombre approach.

Valtteri Bottas is quietly spoken and does not wear his emotions on his sleeve. Like Hamilton, he wanted to drive from an early age, though he admits his career is the result of a fortunate coincidence.

Driving through Nastola in southern Finland - the nearest city to his home and with a population of 15,000 - with his dad Rauno one summer, they spotted a kart track and decided to take a look.

They spent the whole day there and, by the end, Bottas was hooked. He was four. His dad made him wait a year before he raced as he could not reach the pedals. Racing is the only thing he has wanted to do ever since.

Now, at age 27, he remains close to his parents and one sister but has left his home country and resides in Monaco with his wife, the Finnish Olympic swimmer Emilia Pikkarainen, 24.

He also finds himself with a drive at the three-time world champions. Mercedes signed him from Williams in January after Nico Rosberg's shock retirement at the end of last season, just five days after winning the title.

The Finn insists that he is quick enough to challenge Hamilton and is not just making up the numbers. He certainly has a reputation for speed.

Finns do make quick drivers. Think Mika Hakkinen, a two-time world champion, and Kimi Raikkonen, who won the title in 2007.

Bottas previously said that the Finnish success in the sport has something to do with the mentality in the country: "It is to some degree driven by the hard winters and the difficult driving conditions, so you have to actively engage yourself to drive, you can't simply get around on auto-pilot."

While karting, he won numerous championships across Europe. When he moved to cars in 2007, he finished third in his debut season in the Formula Renault 2.0 Northern European Cup, and dominated the next year.

It was around this time that he came to the attention of Toto Wolff, now the head of Mercedes Motorsport but previously a director at Williams.

Wolff offered him backing and management, alongside two other respected men - Bottas' childhood hero, Hakkinen, and Didier Coton, Hakkinen's long-time manager.

Bottas quickly moved up the formulas. In 2010 he signed as reserve driver for Williams and, a year later, he raced in GP3 and took the title.

His consistency and speed earned him drives in the practice sessions on the Friday of race weekends, often outperforming Pastor Maldonado, the more established Williams driver. He was rewarded with a Formula One seat in 2013.

However, that success in the lower tiers has not yet translated to success at the pinnacle. Bottas has competed in 78 grands prix during four full seasons but has yet to win one.

He has sprayed the champagne from the podium nine times but has only ever got as far as the second step (twice). Hamilton, in comparison, has competed in 188 grands prix in 10 seasons, winning 53 races and three world championships.

"It's going to be a difficult year against Lewis," Bottas says.

"He's a great driver and a champion and I haven't won a race so in theory the odds are for him. But I know what I'm capable of in a winning car."

He has a one-year contract with Mercedes with an option for next year, if he can perform.

He knows that established drivers and world champions, such as Fernando Alonso and Sebastian Vettel, are out of contract at the end of this season and could be looking for the seat.

"I know this is a special opportunity and I have a lot of things to prove to secure my place for the long term," he says ahead of the season opener - Sunday's Australian Grand Prix in Melbourne.

"That's how it goes. I'm fine with it. It's a massive opportunity for me this season to prove myself. I'm only here to win. That's the only thing."

THE TIMES, LONDON