Nico Rosberg has gone some way to explaining his impending departure from the Williams team by claiming that he doubts it can recapture the glory it enjoyed in the 1980s and '90s.

Having been linked to a number of teams for 2010, Rosberg finally confirmed the expected on the eve of the inaugural Abu Dhabi Grand Prix, announcing that he would be leaving Williams, although he was unable to divulge the identity of his new employer. With German roots, however, the son of 1982 F1 world champion Keke is expected to wind up with one of two Mercedes-powered teams, either McLaren or, more likely, Brawn.

"My future hasn't been decided yet," he admitted to Britain's Metro newspaper, "I've been with Williams for a long time and it will be hard to leave because we have had such a good understanding and mutual respect, [but] I don't know if they can produce a car capable of winning the championship again. They can build a good car certainly, but I'm not sure it's possible to make one which can go all the way."

Williams' 'problems', Rosberg muses, won't be helped by the apparent strength of certain rivals, including both of the teams he has been linked with.

"It appears [that we're heading to a 'big four' situation]," he noted, "McLaren, Brawn, Red Bull and Ferrari are pulling away from the pack all the time and the rule changes aren't really going to affect them too much, so I can only see them stretching their advantage in 2010. It is going to be difficult [to make the podium in Abu Dhabi] because there are at least six cars that are faster than us at the moment in McLaren, Brawn and Red Bull, so I'm just hoping to get some decent points - but it will be very tough."

Despite remaining tight-lipped about his possible move to Brawn, Rosberg diplomatically recognises the impact the phoenix that rose from the ashes of Honda has made this season.

"Jenson [Button] had a fantastic season - he did a good job for his team and was a worthy winner," he reflected, "It was an amazing story for Brawn GP. Their build-up to the season made all the difference because they obviously put in a lot of effort to build a great car and then carried on developing that car during the season.

Despite expecting to be giving chase to both McLaren and Brawn this weekend, however, Rosberg insists that he will not simply be going through the motions at Yas Marina.

"Not at all, there are still a lot of important things going on," he concluded, "We're sixth in the constructors' championship and BMW Sauber is only two-and-a-half points away, so it's important we stay in front of them.

"For me, I'm seventh in the drivers' championship and I need to defend my position because Jarno Trulli is only four points behind me. There are still a lot of things at stake, so the team is fully motivated and I will be pushing very hard. When the race is over, I won't start testing again until next year, so there is plenty of time to relax."