Rehab

Unlike the Amy Winehouse song of the same name, this "Rehab" is metaphorical. Rihanna has fallen too deeply in love and gotten burned, so now she needs to check into rehab to get over him, as if he's an addiction or a disease.

This song was written by Justin Timberlake, Timbaland and Hannon Lane. Timbaland also produced the song with Lane and contributed backing vocals with Timberlake on the tune's bridge ("ladies, gimme that..."). The Timberlake-Timbaland team were coming off Justin's FutureSex/LoveSounds album, with the hits "SexyBack" and "What Goes Around... Comes Around."

Rihanna told Entertainment Weekly how this song came together: "Well, Timbaland was on tour with Justin and we had to follow Timbaland, really. So we went to Chicago first and one night after the show, Justin just came into the studio and he started messing around, making a beat. And it was fun. We played around with that one, too. And when we came to New York, Justin came back to the studio and he was like, 'I wanna write this song for Rihanna.' So Timbaland had an idea and he knew he wanted to call the song 'Rehab' and he had a beat. So then Justin Timberlake came in and he just put his thing on it. He wrote the song in his head. He didn't write anything on paper. He went into the booth and sang it and I was very, very impressed. We all loved it."