Lewis Hamilton has fired a warning to rival Sebastian Vettel by insisting he is entering the final stretch of their championship battle in the strongest mindset of his career.

Hamilton is 40 points clear of the Ferrari driver ahead of Sunday's Russian Grand Prix, which plays host to the opening round of four races inside just five weeks.

The British world champion, 33, has been in the form of his life in recent times with a scintillating win on Ferrari's home turf at Monza followed by an against-all-odds pole lap in Singapore and a commanding victory.

Hamilton has not returned to Europe since his triumph at the Marina Bay Circuit following work commitments in Thailand, Borneo and Malaysia, and a break in Dubai with American rap star Nicki Minaj.

Both Hamilton and Minaj, who the Brit teamed up with to help launch his Tommy Hilfiger fashion collection in New York earlier this month, posted pictures riding a sand buggy to their respective Instagram accounts.

"I feel healthy, happier and stronger than ever," Hamilton said. "It still feels like it has been a long year.

"But I have had plenty of time to myself, and some really good quality time with family. I also got to see some beautiful places and get some good training in, too, so I do feel really good for this last stint.

"First and foremost, I am a racing driver. I am also trying to grow into an entrepreneur and a businessman and be successful in business, but one who drives the socks off his car."

Hamilton's back-to-back triumphs in Italy and Singapore means he arrives in Sochi having won four of the last five rounds to tighten his grip on a fifth world championship.

But with 150 points still available, Vettel has not given up hope of beating the Mercedes driver to what would now rank as an unlikely title.

"We have a fair chance," he said. "Anything is possible.

"It's very simple from where we are. We are some points behind and we need to catch up to make sure we stay there. That's our target and the best way to do that is to finish ahead, and ideally ahead of everybody."

Vettel might take some encouragement from Hamilton's troubles here last year. The British driver was mysteriously off-colour all weekend, qualifying only fourth – behind both Ferrari cars and his Mercedes team-mate Valtteri Bottas – before taking the chequered flag in the same position.

Last year's race in Russia was only the fourth of the year. Hamilton was still getting accustomed to his Mercedes machinery, and he believes the result is unrepresentative of what is to come this weekend.

"I do believe we are in a better position than we were last season," Hamilton added. "It is still a challenge to get right, but we will take our understanding of last year with a pinch of salt.

"The car is different and we have got a different tyre this weekend, so I assume that we will be faced with different challenges than in 2017."