SUZUKA, Japan (REUTERS) - Sebastian Vettel said on Thursday (Oct 5) that his Ferrari team will have to be at their best if he is to overhaul Lewis Hamilton in the Formula One world championship battle.

"I think it's pretty clear we need to do our best," the German, who trails his Mercedes rival by 34 points in the overall standings with five of this season's 20 races to go, told reporters at the Japanese Grand Prix.

"We need to score more than them. How we achieve it, it doesn't matter, as long as we achieve it.

"But obviously it's much more straightforward if we get our optimum and ideally win a lot of races, then we'll have a better chance."

The last two races in Singapore and Malaysia have been particularly costly for Vettel, winner of four races this year to Hamilton's seven.

The 30-year-old crashed out on the opening lap in Singapore, letting Hamilton through to win from fifth.

He finished a remarkable fourth in Malaysia after having started last due to a power unit problem in qualifying, but dropped further behind the Briton who finished second behind Red Bull's Max Verstappen.

Having gone into last month's Italian Grand Prix in the overall lead, Vettel has lost 41 points to the three-time world champion in the last three races.

If Hamilton, winner of three of the last four races, leaves Suzuka with an advantage of at least 29 points over Vettel, he can potentially beat the German to the title without stepping on the top step of the podium again.

But the four-time champion can draw encouragement from the speed Ferrari displayed in Malaysia, where he set the fastest race lap and a lap record on his charge through the field.

Vettel, who can already take heart from news that he won't need a new gearbox after a bizarre post-race collision with Williams rookie Lance Stroll in Malaysia, expects Ferrari to be competitive this weekend even if Mercedes rediscover their lost pace.

"The last three years I think we were competitive, but not competitive enough to win," he said, expressing confidence that the engine issues that struck him and team-mate Kimi Raikkonen in Malaysia had been resolved.

"This year it's different."