Spears and Harris
INF; Kevin Mazur/WireImage
"She has a good sense of comedy, and has interesting choices," he tells PEOPLE. "It wasn't like she has just been told to stand up there and deliver those lines. I was really surprised by that. She's really funny!"
Harris, who will be on set Thursday filming with the pop star, added, "She seems to be doing very well … No strange accents. She seemed comfortable."
Harris tells PEOPLE that when the pop star's team approached the show producers for the part, "everyone was flabbergasted. We didn't think she wanted to act." But, the cast welcomed the opportunity. "I want to allow her to show a different side of herself. We're proud of her desire to change her image."
