Valtteri Bottas doubted himself during 2017 F1 slump

While team-mate Lewis Hamilton took control of the championship battle with four wins from five grands prix after last year's summer break, Bottas started struggling to get the Mercedes to his liking and fell off the pace.

He arrested that slide with pole for the penultimate race in Brazil and then a win in the Abu Dhabi season finale, but admits his run of poor performances had been mentally draining.

"After struggling quite a lot for a couple of races, it wasn't easy mentally because I was quite confused in the beginning - like, 'what's going on?'," Bottas told Autosport.

"For sure you also start to doubt what you're doing.

"Then also when you need to change some things with your driving style and need to adapt to many different things suddenly you realise it's not that simple.

"Then you easily overthink things and then it becomes less natural driving.

"But it's going to a much better direction. If there's going to be similar struggles [in 2018] I'm prepared for that.

"And I've learnt massively from those difficult races so I think I'm a lot better driver as well than for example in Spa or Malaysia or Japan."

Though F1 underwent a huge change in aerodynamic regulations for 2017, Bottas believes the fundamental characteristics of the Mercedes remained consistent with the cars Hamilton had driven for the previous four seasons.

But having switched from Williams at short notice to fill the gap created by Nico Rosberg's shock retirement, Bottas said his Mercedes experience deficit to Hamilton became very apparent when he hit difficulties.

"What he's been doing better than me, I think it comes mainly from experience," said Bottas, who underlined that there are "definite differences" between their driving styles.

"I think ultimately mechanically the car hasn't really changed much from the last few years, in terms of how it behaves, and it was very different how the Williams car behaved.

"So there's been many things for me to learn, and I've been kind of catching up on things all the time."

He believes he will be "a much more complete, much quicker driver on average" in 2018 than in '17 now he is familiar with Mercedes.

Bottas added that while Hamilton's team familiarity and natural pace had been factors in the gap between them in 2017, the now-four-time champion's work ethic also deserved praise.

"I always knew that he's really talented for sure, and he's quick in any circumstances always - he just goes in the car and he's very quick," said Bottas of Hamilton.

"But that also comes from hard work, he works hard with the team."