[WATCH] Hamilton dominates Japan practice after crash scare

But the reigning world champion, who leads his Ferrari rival by 50 points with five races left this season, survived a close shave in the morning session at Suzuka when he deftly avoided smashing his Mercedes into Pierre Gasly's Toro Rosso.

Hamilton went on to clock a fastest time of one minute, 28.691 seconds before the Briton produced a sizzling lap of 1:28.217 to top the timesheets in the afternoon, almost half-a-second quicker than team-mate Valtteri Bottas.

"This track is awesome," whooped Hamilton over team radio. "I'm having the best day!"

Vettel was third fastest, more than 0.8 seconds off the pace, as he prepares for what is looking increasingly like a must-win race for the German.

Hamilton's only scare came in a bizarre incident early on when he was forced to react sharply to avoid smashing into the back of Gasly's dawdling car on entry to the chicane.

He waved angrily at the Frenchman after veering off the road and later needed to pit to fix technical gremlins after a sensor alarm went off on his car's dashboard.

However, neither issue made much difference to Hamilton's crushing dominance and the pace shown by Mercedes suggests they will be favourites to lock up the front row in Saturday's qualifying, as they did in Russia last week.

Hamilton controversially took his eighth chequered flag of the season at Sochi after Mercedes ordered Bottas to let him through to close in on a fifth Formula One crown.

On Friday's showing, he will fancy his chances of twisting the knife into Vettel, who has seen Hamilton win five of the last six races.

But Mercedes team boss Toto Wolff attempted to play down the significance of the gap to Ferrari.

"I think probably the lap time flatters us a little bit," he said. "But we'll see how it is in qualifying tomorrow."

Vettel, who also had a near-miss with Gasly as he went only fifth fastest in the morning, could be thrown a lifeline by the weather.

An approaching typhoon could hit Suzuka on Saturday, but it would still be difficult to back against the Silver Arrows.

"It has been a clean Friday," insisted Vettel, despite complaining of blistering tyres.

"No interruptions, no issue with the car or anything, so now we have to try to obviously squeeze out everything that is left in the car for tomorrow."

Meanwhile, Red Bull's Max Verstappen went fourth fastest in the afternoon, more than a second off Hamilton's time with Ferrari's Kimi Raikkonen fifth.

Daniel Ricciardo's Red Bull slotted in behind Raikkonen on the timesheets to complete a predictable top six.

Esteban Ocon's Force India was seventh fastest in both sessions, followed by the Haas of Frenchman Romain Grosjean. Marcus Ericsson moved his Sauber up one spot to ninth with Brendon Hartley squeezing into the top 10 for Toro Rosso in the afternoon.