2011 title win for Mercedes 'difficult' - Schumacher

Michael Schumacher has admitted it will be "difficult" for Mercedes to triumph in 2011.

The seven time world champion returned from retirement last year and had a troubled comeback season with the German marque.

Mercedes GP is looking more confidently into its second season since the Brawn takeover, but so far the pace and reliability of the new W02 has appeared less than perfect.

"We are Mercedes and our goal is clear," Schumacher is quoted in German by sport1.de. "It will be difficult to achieve our goal this year but we have a vision that is not only short term."

Schumacher ended a day of the recent Jerez test with the fastest time, but it has been rumoured that it was achieved with low fuel on the super-soft tyre.

"Only the first race in Bahrain will show us exactly what our situation is," said the 42-year-old.

Schumacher's teammate Nico Rosberg has occasionally sounded pessimistic since the debut of the 2011 car, but he told F1's official website that he is not panicking.

"Yes, we weren't too fast in Valencia but with Michael's two days of running in Jerez we are obviously heading in the right direction," he said.

Rosberg said last week that the W02's current specification is akin to an "interim car", with a big step scheduled for closer to the Bahrain opener.