The duo have called it quits after a two-year romance, according to Us Weekly magazine.
'They broke up recently,' said a source close to the New York Yankees slugger, 36.
The actress and sportsman were regularly spotted on the beach and working out together in Miami and New York.
But pals claim their ruthless work schedules got in the way of the relationship.
'She's very busy with her career,' a source said of Bad Teacher actress Diaz, 39. 'And he's had injuries and wants to focus on his game. They're dedicated professionals.
'They're still very friendly and like each other,' the source says. 'They have an enormous amount of respect for each other.'