As conditions changed repeatedly in the pole shootout, the pair only got up to second and third behind Hamilton's Mercedes in the final moments.
"I saw Lewis catching up and thought OK, I could go a bit quicker," Vettel admitted.
"It was close but in these conditions anything can happen.
"It's a shame to miss pole, but really I am quite happy today."
Webber was equally pleased to avoid the session's pitfalls.
"It was difficult for all of us to make the right calls, in the end we got most things right," said Webber.
"It's a difficult thing to know where you are and how the track is moving around.
"It's quite a ballsy thing to go slow on the middle lap knowing the track will be better on the last lap.
"It was quite tight and I'm happy to be up there for tomorrow's race."
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