LEWIS Hamilton lamented a “very unusual” weekend after his abject performance at the Russian Grand Prix saw him slip further behind Sebastian Vettel in the race for the Formula One championship.

Hamilton finished only fourth, a bruising 36 seconds behind Mercedes team-mate Valtteri Bottas, who claimed the first win of his grand prix career at the 81st attempt following a masterful performance.

Bottas, new to Hamilton’s Mercedes team this year after replacing defending champion Nico Rosberg, held his nerve in a nail-biting ending at the Sochi Autodrom to keep Vettel at bay and become only the fifth Finnish driver to win in Formula One.

But it was Hamilton’s sluggish form, at a circuit which he has won on two occasions, which will leave the Briton searching for answers.

Hamilton was out of sorts all weekend as he struggled for the right balance with his car. He is now 13 points behind Vettel, and on Sunday night appeared at a loss to surmise his abnormally off-colour display.

“I can’t explain it right now, but we will do some work over this week to fully understand it,” Hamilton said.

“It is not important to think about the championship because right now I need to understand where the speed was this weekend, where I went wrong with the set-up, and then come back fighting for the next race.

“There is still a long way to go. I am still second in the championship, so it is not the end of the world, but of course I need to recover the pace that I had previously because it was a very, very unusual weekend.”

For Bottas, he arrived at the fourth round of the championship facing question marks over his position at Mercedes after he was ordered out of Hamilton’s way in Bahrain.

But the 27-year-old, who was plucked from Williams to fill Rosberg’s championship-winning seat only in January, responded in exemplary fashion and must now be considered as a real threat, not only to Hamilton, and his de facto number one status at Mercedes, but perhaps Vettel, for this year’s title, too.

‘’For me winning the championship is the only goal in my career so we will keep pushing for that,’’ Bottas, who received his winner’s trophy from Russian President Vladimir Putin, said. ‘’I am not that emotional but hearing the Finnish national anthem is something quite special.

‘’It took quite a while to win – more than 80 races for me – but it was definitely worth the wait and worth the learning curve. This strange opportunity came to me in the winter to join this team and they made it possible today.”