AceShowbiz -

What do Justin Timberlake and John Mayer have in common besides their music career? They both are the ex-boyfriends of Cameron Diaz and they as well also offer the movie star friendly support following her father's death last week.

Justin and John were both seen attending the memorial service of Cammy's late father, which was held Sunday, April 20 at Mahe in Seal Beach. Both music stars attended the service separately and stayed until most people started leaving at around 4 P.M.

"Most people started arriving at 1:30 and hardly no one wore black," a source told People. "Lots of people were wearing Hawaiian shirts. It looked more like a party."

Cammy's father, Emilio Diaz, died suddenly of pneumonia on Tuesday morning, April 15. Having the production on her latest film "My Sister's Keeper" been shut down to give her time to grieve and take care of family matters, Cammy also canceled an appearance at an Elton John-hosted party Wednesday night, April 16 celebrating British GQ, where she's been featured on the cover of its latest issue.

In related news, Cammy and her family have suggested mourners, in lieu of flowers, to show their support to their family by making donation to her father's favorite organizations, Surfrider.org and Reefcheck.org.