Valtteri Bottas admits he has work to do to close the gap to Mercedes teammate Lewis Hamilton following Friday practice for the season-opening Australian Grand Prix.
The Finn, who replaced the retired reigning world champion Nico Rosberg at Mercedes ahead of the 2017 season, was second and third quickest in the first and second practice sessions, though he trailed his new teammate by over 0.5s on each occasion.
When asked to explain the substantial gap to Hamilton, Bottas replied: "It's only practice, but I feel I have work to do in the shorter runs -- for me that's what I have to focus on. I was quite pleased with the long runs, in terms of pace, but in the short runs I was affected by a yellow flag, but, having said that, I still have work to do. There's no particular area where I was losing out, but I know I have work to do."
Bottas acknowledges he is in for a tough fight against Hamilton throughout the year but remains confident he can reach the three-time world champion's level before too long.
"[It will be] a tough fight! That's what's to be expected when you're in a fight with Lewis, it's never easy to try and be at his level of speed," Bottas said. "But that's always the target, today was just the Friday of the season and let's see how things develop. I'm allowing myself a bit of time to get into it and I'm sure I'll get there."
Mercedes' strong showing on Friday came as a disappointment to those expecting an instant challenge from Ferrari, following the Scuderia's impressive performance across the winter, though Sebastian Vettel did manage to split the Silver Arrows duo in second practice.
Despite Mercedes' apparent early advantage, Bottas says it is too early to judge the pecking order for the season and is refusing to underestimate the threat from rivals Ferrari.
"I don't know. It's only Friday but it seems OK, we're looking good. I have to say the car felt better than at the end of testing in Barcelona, but Ferrari looks to be the closest to us and we don't know how much faster they can go, how much fuel they had on board and how much more they can turn up their engine. We're not underestimating them but it will be tomorrow afternoon that we'll see where we are."