Portia de Rossi has moved in with comedienne Ellen DeGeneres after they both left their respective girlfriends to be together.

The couple met on a photo shoot in March and then again at VH1's Big in 04 this month where, a source told the New York Post, they "raced to a limo and fooled around for hours."

They are now living together in Ellen's mansion after her girlfriend of four years, director Alexandra Hedison, moved out a few weeks ago. De Rossi left partner singer-songwriter Francesca Gregorini to move in.

Industry insiders reckon that the relationship will be a short-lived fling. "Ellen will come to her senses and dump Portia to go back to Alexandra in the near future," said one opinionated source.