A bullish Valtteri Bottas says he is determined to beat Lewis Hamilton in 2019.

The Finn was disappointed with his performance last year, and could lose his place at Mercedes for 2020 to new team reserve Esteban Ocon.

Bottas admits that his new look is a signal of his intention to turn things around in 2019.

"I did not shave in the winter, I liked how it looks and it fits with what I want to convey," he is quoted as saying at the Barcelona test.

Bottas said he told himself after last season that "This will never happen again".

"I'm ready to do what's necessary this year to achieve my goals, and if I have to work harder in some places, that's part of it," he added.

Many observers believe Bottas needs to drop the 'nice guy' personality in order to beat Hamilton.

"If he wants to be on an equal footing with Lewis, he must try to be more of the villain," Nico Rosberg, who beat Hamilton to the title in 2016, told Kolner Express newspaper.

"I was naturally not like that either so I had to learn the hardness of my colleagues," he added.

Bottas is showing every sign that he is willing to do that.

For instance, he says he will no longer always fall in line with a team order as he has at times at Mercedes.

"In that situation, if I was there again, I would act differently," Bottas confirmed.

"I only have one career, and if I always support instead of attack for myself, I will never reach my goals," he said.

"I've been in F1 for six years now and I'm not where I want to be. I want to be able to say at the end of the year: I did everything. I could not have done better."

When asked if he has consulted with a psychologist for help, Bottas answered: "Just one -- the man in the mirror."

Finally, 29-year-old Bottas admitted that Ferrari is currently ahead of Mercedes in the winter testing pecking order.

"No matter what settings or the fuel, Ferrari seems to be very fast," he said.

"But everyone's car will be different in Australia, so things can look different by then."