Daniel Radcliffe feared he would get an erection while shooting his first sex scene.The 18-year-old star confessed he had a crush on his "beautiful" 'December Boys' co-star Teresa Palmer and was nervous about getting too sexually aroused when they simulated lovemaking.He told Britain's The Guardian newspaper: "Teresa is beautiful, so I was sort of worried about, you know, certain things. But kissing someone on camera is just not sexy, no matter how attracted to them you are."No matter how beautiful they are, when you're surrounded by crew who are taking measurements of the focus and making sure you're in the right light, it becomes totally clinical. And clinical is not a word I would associate with any good sexual experience."Despite his concerns, the 'Harry Potter' actor loved shooting the "clumsy"sex scene for his new movie - about four orphan boys who want to be adopted by the same family - because it reminded him of his own first sexual experience. He said: "I love that scene! It was so totally clumsy. It's so malcoordinated when she asks him to kiss her neck and play with her tits at the same time. It's that first time experience when you're like, 'OK. What's this hand doing? What's that hand doing?' Trying to coordinate all those things at once is an absolute nightmare. It's a sex scene that's not sexy.It's clumsy and sweet."Daniel added he had no qualms about appearing completely naked on the London stage for his role in the play 'Equus' earlier this year.He said: "If the script says I have sex, I have sex. That's just what you do as an actor."