Reigning world champion Sebastian Vettel admits that he faces a long, hard battle if he is to retain his crown for another year.

Speaking at a press conference shortly after this morning's unveiling of the car with which he and teammate Mark Webber will defend Red Bull's title, the German told reporters: "It's a difficult situation because last year we just said 'let's go for the title', now we want to defend it.

"It will be a tough battle ahead," he continued, "a long, hard fight. Motivation is not a problem, but we need to focus again."

Outside, the sound of engines filled the air as the first of four pre-season test got underway, the season opener in Bahrain just a little over five weeks time.

"We've a lot of testing ahead of us, a very long season," he said, "but we are all pumped and happy to go racing again. What we achieved makes us all very proud, and no-one can take it away from us, so that's a huge plus. This year is a different story - we have to develop from how we were last year otherwise we will be taking a step back and others will pass us. We have to stay focused, try to learn every day, to improve. We have to move forward again."

Referring to problems within the teal last season, problems the necessitated a couple of 'clear the air' meetings, the German said: "Obviously it was very hard in the middle of a season when we were all achieving some pretty big things to tackle and learn about some of the things that went on. But as a group we went through a huge amount last year, and we certainly all learned from that. I know I certainly did.

"So the way I am approaching this year is head on again," he admitted. "I've a great opportunity, and a great team around me, to try to improve on what I did last year. There are a lot of things I did right last year, some very proud moments, with 80% of my season in the middle being good. So it's a case of trying to improve on those things, and go for it."