Valtteri Bottas admits he was doubting himself during the dip in performance he had in the second half of 2017.

The Mercedes driver had proven a worthy replacement for Nico Rosberg alongside Lewis Hamilton, often keeping his teammate on his toes and beating him in some cases, taking wins in Russia and Austria.

The Finn was just about in title contention too after the summer break, but as the Brackley team struggled to cure all weaknesses with their 'diva' W08, Bottas lost his way, struggling to get within half a second of the eventual world champion in qualifying.

“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?’,” he told Motorsport.com.

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

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The 27-year-old would regroup in the final races, taking a third and final win of the year in Abu Dhabi, but now finds himself under pressure with just a one-year extension to his contract and plenty of drivers vying for his seat.

Should he find himself facing struggles again, however, Bottas feels much more prepared.

"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,” he claimed.

The former GP3 champion also thinks the knowledge Hamilton has of how the Mercedes behaves in certain situations played a role in the speed difference between them.

“What he’s been doing better than me, I think it comes mainly from experience. 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," Bottas claimed.

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