The 38-year-old 'The Descendants' actress said Lopez glowed without any make-up on the set, reported Radar Online.
When Lopez showed up on set, "she didn't have any makeup on at all and her hair was just pulled back into a wet bun. I remember thinking that she was so beautiful. I thought, 'What does she do to look so pretty?," Greer said.
The actress said Lopez needs to have security around her all the time.
"And it was so crazy when she got to the airport in baggage that they had to get airport security and cops to come. Since then, she's had to have security all the time," she added.