When Justin Timberlake, 25, was casting the femme fatale for his new $1 million video, “What Goes Around,” the singer who was on the rocks with girlfriend Cameron Diaz went after one actress Scarlett Johansson. And she readily agreed, an odd choice for the seasoned thespian who’s known for her careful film choices.

But not if you have a crush on the leading man, says a pal of Johansson.

“Scarlett has always liked Justin. They’ve always had a flirtation – that’s why Cameron was threatened by her.”

With good reason. The decision to cast the 20-year-old as the video vixen pushed Timberlake’s relationship with Diaz to the breaking point, and paved the way for Johansson to move in for the kill.

“She could not believe he went behind her back to put her in the video,” says a Timberlake pal. “Cameron was very jealous of Scarlett.”

Adds the source, “they definitely got together after she did the video.”

What happen to Cameron Diaz and Justin? Or better yet Josh and Scarlett? Well these two look hot together, back in the Justin and Britney days.

Justin Timberlake spent his holiday at home in Tennessee, surrounded by his close-knit family, including mom (and onetime manager) Lynn, stepfather Paul Harness and his three younger half-brothers.

Cameron Diaz, his girlfriend since 2003, went skiing in Vail, Colo., with her family.

Sources say the glamorous due broke up and went their separate ways after a serious discussion that ended with Justin deciding that his days with Cam were numbered. “They had been planning to be together in Tennessee with his folks,” says a source. “But he came out alone and she stayed in L.A.” And on Dec. 23, as he partied with friends in Senses nightclub in Memphis, the source says, Justin told fellow revelers: “Me and Cameron? We’re done.” He also confided to those friends that “the breakup is for keeps!”

I knew this was gonna be over soon. Ever since Cameron said she wouldnt ever marry Justin. I thought that was a low blow there. How can you go out with someone and say that to the press. I dont get it, but maybe their relationship was long gone by then. It could be a rumor cause STAR is the only one reporting it but still

Cameron Diaz insists her relationship with Justin Timberlake is great, despite claims they barely spend any time together.

The actress credits the couple’s ability to evade paparazzi photographers for the rumors of a split.

Diaz says, “I think it’s the lack of photographs of us together that gives that perception.”

Always fun playing games with the paparazzi, especially that ruin your lives with no privacy! Thank god in the US its not as bad as London. But still anyone hot and young they follow them, in California. Maybe they need to move to Texas and no one will ever see a photographer. Kudos to Cameron!