LONDON, England - Ross Brawn says he remains in charge of the Mercedes Formula 1 team despite the arrival of Toto Wolff as executive director.Mercedes' parent company Daimler has decided to shake up the management structure in the UK-based team with Wolff arriving from Williams and taking a stake in Mercedes-Benz GP.Three-times Wworld champion Niki Lauda, a current non-executive chairman of MGP, will also acquire shares in the company but Brawn is adamant that his authority has not been undermined.'COMPLEMENTARY THINGS'"Toto is coming in and there is another side of the business that, quite frankly, I don't want to get involved in," he said on Thursday. "I don't want to get involved in the commercial activities and with the support we need to give Daimler on a day-to-day basis."There are a lot of things Toto will be doing which are complementary to what I am doing in terms of running the team but you have to have one reference. Everybody knows the only way a racing team will work is to have one reference, and I'm that reference."I am the team principal and I am in charge of sporting, technical and racing matters."Brawn was speaking on the day new driver Lewis Hamilton addressed his Mercedes colleagues for the first time at their base in Brackley, central England. The 2008 F1 champion, who left McLaren at the end of the 2012 season, said he had been given assurances by Brawn that the 58-year-old's role would not be changing."I don't read all the stories that come out but if I've any problems or I do hear any whispers then I can give him a call, which I did, and he set me straight right away," Hamilton said. "We already have that kind of good relationship. We have had a respectable relationship for some time now."From the beginning I said I'll always be blunt. It's important we have an open relationship. That's the way best way to start and he was positive about that.ONLY ONE WINThe English driver said he did not feel as if he was joining a team in turmoil. "No, I don't think it is," he said. "Everything feels really positive. Today is the day I get to speak to the team, I have been around and about, and there is a great spirit here. The guys seem hungrier than any group of people I've seen before. They seem seriously hungry to win and excited they have another shot at it this year."Mercedes has won only one GP since returning to F1 three years ago but Hamilton says he is prepared to be patient while the team strives to improve. "This is a marathon, not a sprint. It's the long haul," he said. "I just hope this year we can be competitive. If we arrive at the first race and we are in front, it's going to be spectacular - if we are not, we know we just have to keep working at it."