Mercedes motorsport boss Norbert Haug has admitted the team has a lot of work to do following another disappointing showing in India.

Mercedes have now gone three races without scoring a single point and while Nico Rosberg did come close to taking tenth, he was passed by the Williams of Bruno Senna late on and demoted to P11.

It is a far cry from the joy of China earlier this year, when Rosberg gave the German manufacturer its first win since taking over the former Brawn GP team at the end of 2009, and with Michael Schumacher also having an event to forget in the sister car, after he picked up a right-rear puncture following contact with the Toro Rosso's Jean-Eric Vergne at the start, there was very little for Haug to smile about.

"Michael suffered contact on the opening lap, which caused a puncture and put him to the back of the field after his pit stop. He retired the car with a gearbox issue five laps before the finish. As for Nico, his car didn't have the speed to score points after starting from 10th position. We have a lot of work to do and everybody in the team is well aware of it," Haug said simply.

Mercedes team principal Ross Brawn meanwhile was similarly frustrated, although he pointed out that with the 2012 F1 field so very, very close, every tenth of a second is now vital.

"We are racing in a closely-matched field this season, where a few tenths of a second in lap time make a significant difference to your position. At the moment, we are on the wrong end of those precious tenths and that once again left us outside the points this afternoon," Brawn added.

"Nico made his one-stop strategy work well, looking after his tyres so that he still had reasonable speed at the end of both stints, but otherwise he had a relatively quiet race.

"As for Michael, the contact at the first corner made it an uphill battle for him from turn two onwards, and left him at the back of the field. However, by running two stints on the option tyre, he was able to show respectable speed at some points of the race."