Lewis Hamilton says performance updates to his Mercedes car have motivated him to push even harder at this weekend’s Russian Grand Prix.

The four-time world champion leads Sebastian Vettel by 40 points in the drivers’ standings and is closing in on his fifth title after winning four of the last five races. He took a solid step towards making it five from six on Friday after setting the fastest time in second practice and finishing the session over half a second ahead of Vettel.

He was helped by updates to the front and rear wing on his Mercedes and said the team’s efforts to improve the car so late in the season had inspired him to get the best possible result from the weekend.

“Sochi has been one of the weaker circuits for me in the past, particularly last year,” he said. “So I’ve done a lot of work to understand the balance and see where I can improve to try and rectify this – today has been good in that sense. From every race we’re learning more and more and particularly the last few races have helped us to really gauge which foot we need to start on for the weekend.

“We’ve brought more upgrades this weekend; there’s so much work going on at home and it’s just really encouraging when you come to a race and you get an upgrade, knowing that this late in the season we’re also already working on next year’s car – it motivates me to get the best out of everything. It’s been a good day for us, so let’s hope that it continues tomorrow.”

Mercedes has won every race in Russia since the grand prix joined the calendar in 2014, but team boss Toto Wolff said he expects Ferrari to put up a strong fight this weekend.

“I never see ourselves as favourites,” Wolff said. “We were beaten in qualifying last year and Valtteri had a really brilliant start, towed the Ferraris and went into the lead.

“And how the season has been going this year, first of all, there’s no patterns any more, and I don’t want to put us in a favourite position, let’s see where we are tomorrow after qualifying.”