"Crossing the line I didn't know whether it was enough or not - a little bit like Abu Dhabi (last year, when he clinched the title at the last race of the season).
"I didn't know where everyone had to finish. Obviously for the next one I am smart enough to work it out myself."
Vettel has finished first or second in all but one of this season's races - and he was fourth in the other, July's
German Grand Prix
So it seems inevitable that he will be crowned champion for the second consecutive year at the Japanese Grand Prix at Suzuka on 9 October.
That would make him the youngest double world champion in F1 history.
Button buoyant after second
Button has moved up in the championship with strong results in the last four races - a win in Hungary, second places in Italy and Singapore and a third place in Belgium.
He said: "I had a goal to beat Seb in the points (counting) from Hungary onward. It's going to be tricky. But I'm the second highest points scorer so far and that's got to be the aim for the rest of the season.
"My main aim is to win races. It didn't quite work here but I was the closest person to do that."
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