Lewis Hamilton says he has “a lot of work to do” to get on terms with the pace of Mercedes Formula 1 teammate Valtteri Bottas at the Russian Grand Prix.

Hamilton finished a lowly 19th during a difficult opening practice session, before recovering to take second in FP2, 0.267s down on Bottas’ session-leading time as the Finn completed a Friday practice sweep.

The Briton, who holds a 55-point championship lead over Bottas heading into this weekend’s race at Sochi, acknowledged he has more performance to find if he is to beat his teammate to pole position for the fifth race in a row.

“I didn’t feel like I was particularly quick today,” Hamilton conceded after second practice.

“It didn’t start off particularly good and P1 was pretty poor. I had a lock-up in Turn 1 on the Soft tyre and then went out on the Hard tyre and completely destroyed the tyres. P1 was scrapped.

“P2 started off better, I’m just down a bit in the first and second sector, but the last one was nice. I haven’t put them all together yet and it’s a work in progress.

“There’s some things I need to improve from the driver’s side and set-up wise. If you don’t take any steps forward in first practice you are starting from behind in the second one.

“Nonetheless, the car has been performing really well. I’ve got a lot of work to do overnight, but it’s nothing new.”

The Mercedes duo were in a league of their own in the afternoon as third-placed man Daniel Ricciardo finished a full second off Bottas’ benchmark in his Renault.

Asked if he was surprised by the margin to the rest of the pack, Hamilton replied: “Yeah because even for us it doesn’t really feel that great out there.

“The grip is poor, there’s a lot of sliding so I’m surprised to see that gap. It must be even worse for those behind.

“But the track will grip up and maybe it will close up tomorrow.”