Lewis Hamilton – making his 67th consecutive Q3 – looked like being fastest, but rain slowed down the final laps of the third qualifying session and the Mercedes driver starts second.
Red Bull’s Vettel admitted he may have had a helping hand from the rain, but is confident ahead of the 70-lap long race.
“It was very, very tricky,” he said. “We’ll be in decent shape as we have tyre left over, so it doesn’t matter too much what the weather is.
“It was a surprise as we expected to get a better run in the second lap, but it started to drizzle going into the last chicane.
“I’m very happy that the lap was good enough as it was very tight with Lewis, luckily for me the last two corners didn’t allow anyone to go quicker.”
A delighted Valtteri Bottas starts third and the novice said it would be a great boost for Williams after a difficult first six races.
However, Paul Di Resta was left furious after a bottom-six finish saw him knocked out in Q1 for a second consecutive grand prix for the first time in his career.
Following on from a disappointing session in Monte Carlo, the Scot will start Force India’s 100th ever grand prix from 17th.
“Something went wrong with the gear box and we spent far too much time trying to fix it when conditions were good and the car could have run,” he said.
“There’s just not much you can do – for a second week running we have not done a good enough job and that needs rectifying.
“I was aware of problem out on the track, why we chose to fix it then is another reason. We need to look ahead and come up with some kind of master plan.”
The downpour also caused problems for Romain Grosjean, who starts last after a ten-place grid penalty, and the Lotus driver was eliminated in Q1 for the first time since Brazil 2012.