The singer/actor co-wrote and produced a number of songs on Madonna's 2008 Hard Candy album.
Timberlake told Metro of Madonna: "She's the most stubborn woman in the world. As a woman, she's the highest in stubbornness.
"But she's very smart and incredibly cerebral. And I think that's why she's been able to change her style and image so much. Her music pays attention to what people are thinking."