Ross Brawn has said he is confident the team's win in Shanghai with Nico Rosberg won't be a one-off.

Mercedes have struggled a bit since China and while team has still managed to add to its tally, Rosberg and team-mate, Michael Schumacher haven't been able to run at the front.

Indeed one fifth place finish and a seventh are the two best results from the last two races respectively in Bahrain and Spain.

"If we take a normal season, there's always some variability between the teams and if you overlay on that the difficulty in getting a good understanding of how to make these tyres work most effectively, then the two together can sometimes bring quite big discrepancies," Brawn explained ahead of this weekend's Monaco Grand Prix.

"Take some of our competitors in Barcelona, they were a second quicker than us, and we were a second quicker than them in the previous race. There's big differences sometimes when these tyres are working or not working properly. I think it's a combination of the two, which makes it quite difficult to always understand where you are in the car and what you have to focus on to improve it.

"But we've done some useful progress with the car I believe, and when we get to those circuits where it would naturally suit the car and we're in the working range of the tyres, then you'll see the performance come back again.

"But it's true the last couple of races have not been so great after we had such a wonderful weekend in China."

Meanwhile, following practice yesterday, Brawn added that he felt they had made a solid start to the weekend.

"We've had a reasonable first day here in Monaco. Obviously, this is a track where conditions are changing all the time and the wet weather in the second session this afternoon reminds us that these things can happen here," he continued.

"We have a lot of information to look at and work out what we're going to do and how we think the circuit will evolve for Saturday. Generally, it's been a good start to the weekend."