The New Zealand centre has sounded out Cooper about joining him and the mercurial Wallaby has kept the door open.
"We've definitely had a chat about it and it's more about playing with each other," Cooper told Fox Sports. "It's something that I'd really like to do in the future.
"And seeing what he's [Williams] done in rugby, and having a talent like that in and around you would be a massive achievement to play with. Whether it'd be in rugby or league it'd be something that I'd definitely be open-minded about."
Cooper signed a three-year contract with Queensland Reds and the Australian Rugby Union earlier this year but his future remains uncertain.
The fly-half will start for Australia this weekend as the Wallabies bid to kick-start their Rugby Championship against South Africa. And he insists his only focus at the moment is getting his side back to winning ways.
"My future right now is with rugby and I've got a lot to achieve right now," added Cooper.
"There's a lot going on this year that I want to concentrate on.
"My job at the moment is being the best No.10 I can be for the Wallabies and then concentrate on my future after that. I've got a manager to do that and that's his job to concentrate and focus on that area."