Fernando Alonso says he is not too scared by Mercedes, despite the team locking out the front row in Spain.
Alonso qualified in fifth place for his home race and reckons Kimi Raikkonen - who starts from fourth - will be a threat.
"It’s a well known fact that Saturday afternoon is our weak point and fifth place is more or less what we were expecting," said the Spaniard.
"We were well aware that Red Bull and Mercedes would both be very strong, but while it’s true we have to start taking back points on Vettel, we are not too scared of Mercedes, who usually have higher tyre degradation. The team and I are optimistic for tomorrow as our race pace is good and usually we manage to go better on Sunday".
"We start from the clean side and hope that will allow us to get off the line well, because what we need here is to make up some places at the start and then put in a few clean laps in the early stages or at half distance. We will also have to defend against Raikkonen: so far he has gone very well in the races and the Lotus doesn’t seem to suffer too much on the tyre front. As usual this season it will be very important to choose the right strategy, because there is only one lap difference in terms of degradation between the two tyre compounds."
Felipe Massa starts ninth after picking up a three place penalty for impeding Mark Webber.
"It was not my intention to get in his way and in all honesty, I can’t recall having affected his qualifying", he said.
"When I saw him in the mirrors, I thought I’d get through the corner before letting him by, which was the only course of action at such a narrow point. On top of that, he was on worn tyres at the time and I don’t think he was doing a quick lap."