Madonna is determined to get all she can out of her new collaborators Justin Timberlake and Timbaland - she's working them around the clock. The pair are working on several tracks on the Material Girl's forthcoming album in a London studio - and admit they thought they would have more free time to check out the sights in the British capital. Timbaland sighs, "We are working around the clock. Justin was meant to be out tonight but he's too tired."