Vettel says weather is his main worry

Red Bull Racing failed to make the most of the wet weather conditions that marred the Australian and Chinese Grands Prix - opening the door for McLaren to do a better job as Jenson Button grabbed victories in both events.

And with Red Bull Racing having just one victory to its name so far season, despite having been on pole position at every race, Vettel is well aware about how his outfit wants an incident-free dry event in Barcelona.

When asked in Spain who he feared the most this weekend, Vettel said: "The weather! I think it was quite chaotic especially the last race, so we try to execute a clean Sunday and a clean race. It doesn't help when it starts to rain and stops raining every five minutes.

"Even then you have to do a good job, and last time we didn't succeed the way we wanted to. But here we will see what we can do."

Vettel insists he does not want to waste any time dwelling on the opportunities that have slipped through Red Bull Racing's fingers in the opening races.

"On Saturdays we were always looking good, but Sundays probably not so much," he said. "That is history and what, could or should [have happened] it doesn't matter. We are looking forward to this race.

"I am trying to show everyone how strong we are, and let's see how we do. For this race it is the same for everyone - you try to bring new parts and try to bring a step forward. We have some new parts and we need to confirm it is the step we think it is, and then we go from there."

Vettel also thinks the fight at the front of the field is much closer than many people believe - even though his team has been on pole at every race.

"McLaren, Ferrari and Mercedes, all three teams look very strong," he said. "It has been very close. In some races we were stronger than others, but in other races it was much closer, then sometimes McLaren was strongest and fastest.

"So it is tough, it is tight. We will make a step here, but it depends how big your step is compared to the others. If you find half a second then great, but if others find one second then it is rubbish."