Justin Bieber's 'Boyfriend' video co-star says he was completely professional during their love scenes.

Rachel Barnes, plays 48-year-old Justin's love interest in his latest music video and she revealed filming the steamy scenes was made easier since they are both in committed relationships, with Justin's girlfriend Selena Gomez even stopping by the set to say hello.

She told 'Access Hollywood': ''It was really professional, really professional. He has a girlfriend and I'm married, so I think that kind of made us comfortable enough to do what we had to do. But it was just more of a good time.

''[Selena] showed up. She was super nice, too. She was having a great time ... tons of music and dancing. It was hard not to have a good time.''

Although Rachel loved working on the video, she admitted it was a lot of hard work too.

She explained: ''[Justin] was so cool ... It was a 13 hour shoot, so not much time for play. It was definitely a lot of work, and he was totally professional. He's got some moves - he's a good dancer.

''Who wouldn't be excited to hang out on a music video set all day with Justin Bieber? He was awesome. It's like all these dancers [were there and] it was just like a giant party on set. There [were] tons of extras and dancing, and we're listening to 'Boyfriend' all day, which I happen to love the song. So it was just bonus after bonus.

''It's just so cool to be part of something this amazing. It's just been such a fun ride. I'm enjoying every second of it.''