Vettel convinced Mercedes sandbagged in Sochi practice

While the Italian squad topped the times both in the morning and the afternoon sessions, Mercedes's Valtteri Bottas finished a distant third in FP2, over six tenths behind Vettel, with Lewis Hamilton further behind.

But Vettel insisted the gap to Mercedes was "artificial" and expects his rivals to be on the pace on Saturday.

When asked if he thought Mercedes was sandbagging, Vettel said: "Yes. I think they will be fine. It's a circuit that suits them so they will be strong tomorrow.

"I think last year people expected Williams to be fastest after Friday, if I remember right, and it turned out Mercedes was the fastest.

"That's how sometimes you can be misled and I think there's a lot of things we can play within the car: fuel loads, engine modes...

"This looks like a Mercedes track. For sure they didn't show everything today and they didn't get a lap together, so the gap you see is artificial."

Vettel admitted he had a rough start to the day in the morning session, when he struggled to get up to speed and even spun near the end of the running.

"I think we can be [happy], but not entirely," he added. "We had a bit of a rough start this morning, got a little bit of out hand with the first set of supersofts, and it took me a while to get up to speed.

"Towards the end I found the car again and I think the pace looks okay, but surely it feels like there's a bit more we can squeeze out, so we need to see where we can find it.

"Set-up wise we didn't change much for majority of the day because I needed to get up to speed and only in the end I think it was okay."

Teammate Kimi Raikkonen was quickest in the morning and finished second in the afternoon, 0.263s behind Vettel.