BRACKLEY, England (AP) -Lewis Hamilton spent his first day with the Mercedes workforce rejecting talk of a management structure in turmoil and expressing his confidence that the team can go from Formula One also-rans to potential champions.

After 14 years at McLaren, the British driver is embarking on a fresh challenge at Mercedes to try to add to his solitary drivers' title from 2008.

However, the early months of his stint at his new team have been rife with speculation that the position of Ross Brawn, Mercedes' team principal, is under threat following a recent reshuffle of the hierarchy and widespread reports of McLaren technical director Paddy Lowe being brought in.

"I've been assured by Ross his commitment is for the long term and he is here to try to win with me, which reassures me and gives me a positive feeling moving forward," Hamilton said on Thursday.

Hamilton was equally sure that Mercedes, which has won just one grand prix since the team's return to F1 in 2010, would be more competitive this year.

"Everything feels really positive for me," Hamilton said. "While 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."