Fernando Alonso has admitted his frustration at the way the 2011 F1 season has started and said 'it's impossible to race' with the new Pirelli tyres.

The vast difference in performance between the different Pirelli compounds had led to added interest in the three races so far, with the laptimes for different drivers varying wildly depending on which tyre they are running on.

Alonso admits that the vastly different performance is making it difficult on track and said that drivers can only focus on their own strategy and try not to worry about others.

"With this year's tyres, it's impossible to race," he told SpeedTV. "You feel competitive, you feel you are doing a good race, and some parts of the race you feel very slow, because there are people who catch you and overtake you without any problems.

"So you need to keep concentration, you need to keep focused on your own strategy. And in the end when you have a quick car, any strategy is good, as Webber showed today. When you have a slow car, everything is more difficult."

Alonso added that his below par performance in Shanghai, where he finished only seventh, was down in no small part to Ferrari simply not having the performance of its rivals.

"It was very bad the start, a lot of wheelspin, and I lost one position," he said. "I had to close the door for the Force India that arrived very quick as well. So we lost a position there. It was not a big problem, because we know this year's races anything can happen with tyre degradation and pit stops etc. But it was not only the start, the race pace was too slow, so unfortunately we lost our opportunity."