According to FemaleFirst, Diaz spent a romantic weekend in New York with Cooper, which sparked rumours that they were a couple.
Diaz and Cooper had dinner together on Saturday evening, and then went to a nightclub called Primehouse.
A witness told the New York Post: "They were very close and lovey. Something is definitely going on, and it’s clear they are more than just friends."
The following day the couple was seen at New York Giants football game with Ashton Kutcher and Demi Moore.