Lewis Hamilton has denied Mercedes "sandbagged" during Friday Practice for the Russian GP and insisted Ferrari are ahead after topping the timesheets by over half a second at Sochi.

Sebastian Vettel's pacesetting Friday lap of 1:34.120 was 0.670s faster than the quickest Mercedes could manage.

"It's one lap, it's much more important what we did after that. I think we improved throughout the session so I'm reasonably happy," the Ferrari driver told Sky Sports F1.

"I think (Mercedes) will be fine, it's a circuit that suits them. Last year, people expected Williams to be the fastest after the Friday, if I remember it right, and it turned out Mercedes were the fastest, that's how sometimes you can be misled."

But Hamilton responded: "We never sandbag, there's no benefit to sandbagging ever - I think Ferrari have done in the past, but there's zero benefit for us to do so.

"Today has generally been a tricky day so Ferrari is definitely the quickest, as they have been all year so far so we work hard this evening and tomorrow try and see if we can pick up some pace."

Tale of the Tape - Lewis Hamilton v Sebastian Vettel

F1 heads into this weekend's Sochi event with Vettel, winner of two of the opening three races, seven points ahead of Hamilton in the Drivers' Championship, while Ferrari are three clear of Mercedes in the constructors' standings.

"I think there's a lot of things you can play with in the car. This track especially there's a lot of things you can show and not show so I think the most important is we talk about ourselves, our balance. I was able to improve so I'm reasonably happy," added Vettel.

Sky Sports F1's Johnny Herbert suggested Mercedes could have been holding back in Friday's Practice sessions.

Former world champion Damon Hill believes this season's drivers race could help define the careers of both Lewis Hamilton and Sebastian Vettel Former world champion Damon Hill believes this season's drivers race could help define the careers of both Lewis Hamilton and Sebastian Vettel

"I think it's maybe something they're not showing by Ferrari, that raw pace that maybe they've still got. It's a program they're sticking to, but they're not showing that pace," he said.

However, Mercedes team boss Toto Wolff insisted the large difference in lap time was not a tactical move.

"I think that we've said it before the race, it's all new, we've been very good on the track in the last couple of years but it changed. The cars have much more down force, the tyres are completely different and you cannot anticipate that it's going to continue so here we go," he told Sky Sports F1.

"I remember Melbourne or Shanghai, we had been a second faster on the long runs than everybody else, it just changed on Saturday then Sunday. Everybody is doing a little bit of a weird program sometimes to find out where they are."

Practice Two didn't run smoothly for Red Bull's Max Verstappen. The Dutchman had to stop on track, reporting a loss of power on the long runs, but remained in fifth, 1.4 seconds slower than Ferrari and ahead of team-mate Daniel Ricciardo.

"We think it was a fuel pressure issue, it was a shame, another not a long run. Luckily Daniel did a long run so we can look into the data for that," reported Verstappen.

"This track is not good for us because of the long straights and yeah we just tried to make the best of it."

Will Ferrari stay ahead of the pack in Sochi? Watch the Russian GP weekend with Sky Sports F1. The race begins at 1pm on Sunday. Check out all the ways to watch live F1 on Sky Sports for subscribers and non-subscribers - including a NOW TV day pass for £6.99!