Lewis Hamilton will be looking to restore normal service at the Japanese Grand Prix after being gifted a controversial victory by Mercedes in Russia last weekend.

But the runaway Formula One championship leader appears to have complicated that task by refusing to rule out leaving Mercedes when his current contract expires in 2020.

Hamilton was allowed to claim a 70th career win when Valtteri Bottas was ordered to move over in Sochi — with the world champion describing it as “the strangest day” of his career.

The Briton, who has opened a 50-point advantage over Ferrari’s Sebastian Vettel with five races left this season, will want to prove he can win in his own right at Suzuka this week as he chases a fifth title.

Vettel called the decision by Mercedes to sacrifice a rare Bottas victory and extend Hamilton’s championship lead a “no-brainer”.

However, Hamilton’s eighth win of the season and third in a row left the Silver Arrows red-faced and sparked fresh debate over team orders with many Formula One fans taking to social media to vent their anger.

Despite the criticism, Mercedes team boss Toto Wolff insisted he had no regrets about issuing the instruction to let Hamilton pass.

“I’d rather be the baddie today than the idiot at the end of the year,” he said.

“Rationally it was the right call.”

Wolff expects Hamilton, who won in Japan for the fourth time last year, to continue his dominance this weekend.

“Lewis is hungry, focused and completely determined to succeed,” the Austrian told reporters.

“It has been great to see the power he has brought to this championship and how he’s taken it to the next level since the summer break.”

But Hamilton has set tongues wagging in the build-up to the race by hinting he could leave Mercedes after his present deal runs out.

“I’ve given them a lot,” Hamilton told Swiss newspaper Blick.

“Mercedes and Hamilton — that’s an almost unbeatable unit. I don’t know, ask me again at the end of 2020,” he added when quizzed about his future.

Meanwhile, Vettel’s hopes of a dramatic turnaround look increasingly forlorn after finishing third behind the two Mercedes in Russia.

A fifth Japanese victory this weekend would be just the ticket for the German, who won four consecutive world championships with Red Bull from 2010 to 2013.

But Vettel, who began the season with back-to-back victories, also knows he needs a huge slice of luck to stand any chance of halting Hamilton’s charge to the title.

“I wasn’t a genius in maths — but it’s not getting easier if we lose points,” he said.

“I still believe in our chances, yes. It takes one DNF (did not finish) and then all of a sudden things look different.”

Kimi Raikkonen can expect an emotional reception from his legion of Japanese fans in his final Suzuka race for Ferrari after learning last month that the team would not be retaining his services for 2019. The Finn will move to Sauber for the next two seasons at least.

Hamilton suggested Ferrari were making a mistake in dispensing with the 2007 world champion, who was the last man to win the drivers’ title with the Maranello team.

“He is an extraordinary professional and a fantastic driver,” he said.

“He remains one of my favourite drivers and I’m convinced that Ferrari is losing a very important driver. It makes no sense to me.”