Red Bull driver Mark Webber has admitted that his team's new car still has some weaknesses.
Christian Horner's team endured some torrid days during pre-season testing in Barcelona, no more so than Sebastien Vettel's final day at the Circuit de Catalunya.
However, the Australian is still confident that the car will be competitive despite admitting that they do not have a clear idea of where they are.
"Performance-wise, we're a team aiming to win, and we know it's a very challenging season ahead against a lot of good, ambitious teams," Webber wrote on the BBC website. "Mercedes, Ferrari and McLaren all need to win. It's going to be fascinating how it turns out.
"It's been incredibly rewarding for the team to be at the level we have been for the last two years, but it doesn't take much to fall off. We work to fine margins in F1, and you might not be as comfortable as you were in the past.
"At this stage, we really don't know if we have done enough. Clearly, we'll be competitive, but whether we're strong enough to win remains to be seen. What we have been able to work out from testing is that all the teams have strengths and weaknesses - including us."
Webber finished third last season behind McLaren's Jenson Button and teammate Sebastien Vettel, who was crowned champion.
