Rosberg was linked with BMW-Sauber
Nico Rosberg has put himself forward as a potential team-mate for world champion Lewis Hamilton at McLaren next season if Heikki Kovalainen leaves.
"I have been a team-mate with Lewis before so that wouldn't be a problem," said the Williams driver, who partnered the Briton in go-karts as a teenager.
"It would be fine and very tough also - a combination, sweet and sour."
Rosberg, son of 1982 Formula One world champion Keke, is out of contract with Williams at the end of the season.
Finn Kovalainen is also out of contract and under pressure at McLaren after failing to realise his early potential.
However, when asked about his position at the team following Friday practice in Valencia ahead of the European Grand Prix, he told BBC Sport: "(Team principal) Martin (Whitmarsh) has said publicly that he hasn't initiated any talks with any other drivers.
"I haven't followed any more into that, I've focused on racing."
I've been finishing fourth and fifth and I want to be finishing first and second and third, which is the next step
The 27-year-old also denied he was already negotiating with other teams, saying: "No, I won't go into that now."
Rosberg, who has scored all of his team's 25.5 points so far this year, was a target of Mercedes-powered McLaren two years ago when they were looking for a replacement for double world champion Fernando Alonso but he was bound by his existing contract.
The 24-year-old German had more recently been linked to BMW-Sauber, but that door was closed when BMW unexpectedly announced last month that they were pulling out of F1 at the end of the season.
"It's one clear option less, that's pretty obvious, but I am still very pleased with my situation," said Rosberg.
"I have various good options and at the moment I am still figuring out what the best way to go is.
"I am close to having a clear picture now of what the options are, I'm still gathering a few bits and pieces.
"I had a discussion with Williams last week to clarify what the situation is. I think sooner or later I'll be able to progress in a specific direction."
Rosberg said Williams were keen to keep him but hinted he would leave.
"I want to go further up," he said. "I've been finishing fourth and fifth and I want to be finishing first and second and third, which is the next step.
"It's a very important step and I need to judge where I am going to get the highest chance of getting that."