Lewis Hamilton has admitted he cannot explain his dramatic loss of pace and performance in the Russian GP.

Hamilton was almost half a second slower than team-mate Valtteri Bottas in qualifying at Sochi and then crossed the line over half a minute behind the Finn on race day as Bottas secured his maiden F1 win.

"I can't explain it," said Hamilton. "We will do some work this week to fully understand it. I have some feelings and some ideas but lots of work will be done to figure it out."

While Bottas' victory prevented the second-placed Sebastian Vettel from further extending his championship lead over Hamilton, the 27-year-old's breakthrough triumph also meant that a mere 10 points now separate the two Mercedes team-mates in the standings.

Two weeks ago, the F1 talk was of a two-driver battle for the title as Hamilton and Vettel surged clear in the Drivers' Championship. Now it seems there is a two-driver battle at Mercedes for Hamilton to contend with as well.

Latest Drivers' Championship standings Driver Team Points Sebastian Vettel Ferrari 86 Lewis Hamilton Mercedes 73 Valtteri Bottas Mercedes 63 Kimi Raikkonen Ferrari 49 Max Verstappen Red Bull 35

"The direction he was able to go I wasn't able to go basically and I don't properly understand why," said Hamilton. "Our driving styles are quite similar so I'm not quite sure what else in the car was stopping me go in that direction.

"Right now I need to understand where the speed was this weekend, what went wrong with the set up and then come back fighting for the next race. But l need to recover the pace l had previously because it was a very, very unusual weekend."

Meanwhile, it wasn't only Hamilton who was stumped by the sudden and unexpected reversal in fortunes at Mercedes. Despite running in third from start to finish in the race, Kimi Raikkonen was heard berating his race engineer upon being told that he was behind Bottas - unaware that it was the Finn, and not the three-time world champion, who had been leading the Silver Arrows' charge to their second race win of the year.

Don't miss all the reaction from Sochi and tune in for the F1 Report: Russian GP Review on Sky Sports F1 on Wednesday night at 8.30pm