Valtteri Bottas admits he had a few doubts during last year's championship but believe he "learnt massively" from it.
Although Bottas had a good start to his Mercedes career, claiming his first race victory in Russia, he went off the boil midseason while at the same time Lewis Hamilton upped his game.
While the Brit dominated after the summer break, winning three races on the trot, Bottas struggled to match his team-mate's form.
And that, he concedes, was concerning.
"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. 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 in 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."
The Finn added that he reckons Hamilton also benefitted from his experience with Mercedes as he understood the car better which meant he was able to find solutions faster.
"What he's been doing better than me, I think it comes mainly from experience.
"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."