Mercedes motorsport boss Toto Wolff admits he hasn't been surprised by the success Valtteri Bottas has had since joining the team at the beginning of 2017.

The Austrian has had a long relationship with the Finn as he was part of his management team while at Williams, where Wolff too was previously a shareholder until switching to Mercedes.

While some had doubts, that knowledge of how Bottas operated was likely one of the key reasons why he immediately became the preferred replacement for Nico Rosberg, something that two wins and five additional podiums have since backed up.

"I'm not surprised," Wolff said of the former GP3 champion's performances this season.

"I've known him for a long time and I knew that his dream was to be in a car that is competitive and that lets him win races.

"When the deal was done I think this was just what he wanted. He got his head down, keeps on working flat out with the engineers at the factory - and he is doing a very good job."

His arrival at Brackley has also done a lot to change the atmosphere within the Mercedes team, as Bottas and Lewis Hamilton have forged a strong working partnership in stark contrast to the growing tension of the last three years.

"Valtteri is very different," Wolff told a fan Q&A comparing Bottas to Rosberg. "He is just interested in the racing. He has a stable family life, a wonderful wife.

"[He] needs his surrounding people: he has [wife] Antti, his coach that looks after him. He has no politics, no war outside of the track.

"I enjoyed working with Nico," Wolff insisted. "He is a challenging personality who has made his way all the way to the top.

"Sometimes you say it was easier for him, but actually I think it was very difficult for him. If you are the son of a World Champion you need to find the energy and the motivation within yourself and I don't think that is very easy.

"But he achieved his lifelong dream and then he decided to call it a day - which somehow is inspirational because we are all on that hamster wheel.

"He is one that actually decided to jump out of it."

Focusing back on Bottas, however, and Toto has now made it clear that with 23 points covering Sebastian Vettel at the top and the 28-year-old in third in the Drivers' standings, Mercedes will continue to allow both he and Hamilton to race freely for now.

"If both of them are in contention for the world championship we will not interfere. That is very clear," he declared.

"There could be a situation that if you come to the end of the championship and mathematically one could still win if he were to win all races and neither Sebastian nor Lewis would score any points, then obviously that doesn't count.

"But until then, and while both of them can win the championship, I'd like to see them racing. I think we owe it to them."