Both Williams drivers will head into the remainder of the Russian Grand Prix weekend in upbeat mood after a strong Friday practice performance suggested they could be a strong threat for points.

Although the start of the season hasn't exactly been bad for the Grove team, it has a gap to close on Red Bull before it can even think about challenging F1's top two teams, but both Felipe Massa and Valtteri Bottas ended day one in optimistic mood after clocking the ninth and sixth fastest time respectively.

"The good run felt good for us so it's positive, but there's still a bit of work to do, particularly in the shorter runs and to understand the tyres," Bottas noted, "It's very difficult here as you do a small front wing adjustment in the pits and, when you go out, you suddenly have massively more grip than in the lap before, so we need to understand why. Otherwise, everything worked pretty well: the front wing looked a bit better, like it should be, the bits we had in the floor were also positive, so I'm pretty pleased with the long run pace. It was a messy run with traffic and everything, but it was not bad."

Happy with his long run pace, Bottas also reckons there's more to come from low fuel running and has one eye targeting Ferrari over the rest of the weekend.

"I think there were some tenths of a second [lost to traffic on my fastest lap] but, even from my side, I haven't managed to get the perfect lap in yet," the Finn admitted, "We don't fully understand the tyre behaviour in the shorter runs, so there's definitively work to be done. Tomorrow, we have FP3 to do some low fuel running, so there's more to come from us but, I'm sure, that will be the case for everybody else.

"From today, however, it looks like we're not that far [from Ferrari], but we shouldn't underestimate them, as they can always be very quick. At least it's looking better than in the previous races but tomorrow we'll really find out, and on Sunday too."

Team-mate Massa, meanwhile, acknowledged that the timesheets may have been tweaked by the numerous spins precipitated by the cold conditions and dusty track, but shared Bottas' enthusiasm for the FW38.

"We sorted the problem I had in the morning, changed what had to be changed and the car worked perfectly in the afternoon," he reported, "I think was a good day for us - the car feels competitive in the short and long runs, compared to Red Bull, and we need to analyse how we compare with Ferrari and Mercedes, which are not easy to be sure about, but I feel confident. The car feels okay, so maybe this can be a better track for us, compared to other tracks."