Motor racing-Vettel's title hopes suffer huge blow in Japan

* Vettel retires in Japan

* Ferrari driver suffers engine problem

* Title favourite Hamilton leads from pole (Adds details, quotes)

By Abhishek Takle

SUZUKA, Japan, Oct 8 (Reuters) - Sebastian Vettel suffered the agony of another retirement on Sunday as his Formula One title hopes disappeared almost over the horizon.

Engine problems forced the German out of Sunday's Japanese Grand Prix on the fourth lap after his Ferrari mechanics had worked feverishly on the starting grid to try and fix an engine problem.

Vettel was already 34 points behind championship leader Lewis Hamilton, with the Mercedes driver leading from pole position and set to stretch his lead to 59 with four races remaining.

"Of course it hurts, and we're all disappointed," said the four times world champion, who hugged his mechanics and gave the crowd a quick wave after returning to the pits.

"Now I think we just have to get back, get some rest and go flat out for the last four races and see what happens."

Vettel had lined up alongside Hamilton on the front row at a sunny Suzuka, hoping the hotter conditions could handicap the Briton after he proved unbeatable in qualifying.

But all was clearly not well, with Ferrari mechanics hurriedly changing the car's spark plug as the seconds ticked away.

The German made a clean start, hanging on to second off the line, but it soon became apparent the problem ran much deeper as Vettel, clearly lacking power, plummeted down the order.

He was finally called in to the pits: "Box, Sebastian, box. We retire the car," he was told.

It was the third race in a row that Vettel's hopes had been dealt a battering.

In Singapore the 30-year-old crashed out on the opening lap after colliding with team-mate Kimi Raikkonen, who had tangled with Red Bull's Max Verstappen.

Two weeks later in Malaysia, the Ferrari driver finished fourth after engine problems in qualifying forced him to start at the back of the field.

Triple champion Hamilton capitalised on both occasions, winning in Singapore and finishing second in Malaysia.

But Sunday's setback could be the most decisive yet, opening the possibility that Hamilton could wrap up his fourth title as early as the next race in Austin, Texas, if not Mexico a week later.

"We still have a chance this year...obviously it's not as much in our control as we would like," said Vettel.

"I think we are improving race by race, we've got a lot further than people have thought so there's also some positives," he added.

"But for sure now you don't look at the positives because it's not the day to look at positives." (Reporting by Abhishek Takle; Editing by John O'Brien/Alan Baldwin)