Rosberg: 'Vettel needs a miracle'

Reigning F1 champion Nico Rosberg says "fighter" Sebastian Vettel will not give up on the title without a battle.

Lewis Hamilton (left) now has a 59 point-lead over Sebastian Vettel in the F1 title race.

Nico Rosberg believes the battle for the Formula One title is still intriguing even though Sebastian Vettel needs a "miracle" to prevent Lewis Hamilton from being crowned champion.

Hamilton stretched his lead to 59 points by winning the Japanese Grand Prix after Vettel retired due to engine trouble only four laps in.

A fourth F1 world title could be wrapped up by Mercedes driver Hamilton at the United States Grand Prix a week on Sunday.

READ: Ferrari chief says Vettel's title race isn't run yet

Reigning champion Rosberg knows it is unlikely that Vettel can deny his former team-mate, but expects Ferrari to hit back in Austin. "Ferrari always come back strong," he said.

"It's so difficult for Sebastian now. Lewis has such momentum, everything is going in his direction. Sebastian needs a miracle to come back but he's a fighter and he won't give up. It will remain interesting so let's see how far he can take it," he added.