Heading into a weekend which could see him put the 2018 title even further out of Sebastian Vettel's reach, Lewis Hamilton admits he's feeling stronger than ever.

"I feel healthy, happier and stronger than ever," the Briton told reporters in Sochi, as he looks to extend what already seems to be an unassailable 40-point lead.

"It still feels like it has been a long year," he admitted, "but I have had plenty of time to myself, and some really good quality time with family, so I do feel really good for this last stint."

Despite the fact that Mercedes appears to be heading towards its fifth successive title, having dominated the sport since the introduction of the hybrid formula in 2014, Hamilton admits there is no letting up, certainly from his side.

"We are all stuck in our ways, it is hard for us to change," he said. "When you work with engineers it is similar and breaking patterns and moulds and challenging people, that's what I live to do.

"I am a pain in the arse to my engineers, because I am always challenging. I like to think it has a positive impact to spring an idea or a direction to push the car."

Though Mercedes has won every edition of the Russian Grand Prix since it joined the calendar in 2014, due to tyre issues the Briton could only finish fourth last season.

"I believe this weekend we will be in a better position than we were last year," he said. "Our understanding of the tyre is far greater than last year but it's still a challenge."

Check out our Thursday gallery from Sochi, here.