David Duchovny first came to prominence as laconic FBI agent Fox Mulder in the wildly popular TV series The X Files, and it wasn't long before the movie suits sat up and took notice. In 1993 he starred alongside Brad Pitt in quirky thriller Kalifornia, and next took the role of a doctor lured into a criminal underworld in Playing God. Opposite Minnie Driver in Return To Me, he showed us a funnier, more romantic, side and even tried his hand at spoof sci-fi with Evolution. Still Duchovny has yet to score a box office hit, although he's having another bash with gender-bending comedy Connie And Carla, co-starring Nia Vardalos.

How did you become involved with this project?

The script came my way and I liked the tone of it very much. You know, Nia Vardalos is a really good writer. She knows her own strengths and how to keep a consistent tone, which is really hard to find in a script. It's hard to find scripts that know what they are from page one to page 115. This feels like the same movie all the way through, and especially with a comedy, that's really hard to do. Usually people write jokes, but Nia was writing characters, and that's what I liked.

Are you a fan of musicals, and cabaret?

Nope. Not at all.

So weren't you wary about getting involved because of that?

You know, when I read the script, I guess I didn't hear the songs in my head - mostly because I don't know them. When I read in the script "they break into song", I didn't hear it because it was just one line in the script. I think the nice thing about the music from my point of view, and others who don't enjoy musical theatre - or don't know it - is this is kind of a 'musicals greatest hits'. It was funny, because we were doing a read-through of the script before the shoot. The director had set up a piano player, and Nia and Toni actually sang. They didn't just say, "Nia and Toni start to sing Cats." I was sat next to Nia and after they did a couple of tunes I kept saying, "That's nice, where's that from?" They were amazed, and like, "Only the most famous musical ever!"

When you do a romantic movie like this, do you just hope that the chemistry is there, or do you have to work on it?

If it doesn't come naturally, it's your job to create it. That's why you're there. I don't think, with this, we have sexual chemistry, and I think that's a misunderstanding of what actors do. Chemistry is really about two people who like to act together, I think. It's like tennis in the most clichéd way. It's like if you hit the ball, they hit the ball back, and they don't hit it into the stands, and they don't put the ball in their pocket and walk off - and they don't argue with the umpire, you know? You want to be acting with somebody where you're just in a flow, hitting the ball back and forth. That's what chemistry is to me, and there are some actors who just fall into a rhythm like that, and with some you have to create it. But with Nia, I thought we had a good rhythm from the beginning. She's very playful and I enjoy that.

The way you see it, when does Jeff fall in love with Connie - before or after he finds out she's a woman?

[Laughs] I like the version where he falls in love with her while he still thinks she's a man, but that's not really what the movie is about. I think it's about becoming friends first. I mean, that's the idea behind this couple falling in love, and that's why he's able to fall in love with her - because he gets to know her as a guy first. But I think it's a little more twisted and a little funnier if he's slightly disappointed when he finds out that she's really a woman.

Did you ever think it was a slightly risky career movie to play a man who falls in love with someone who is, ostensibly, another man?

Mmm... no. No, I don't think so [laughs]. God, I never thought of it that way.

You've had great forays into comedy, more so with television, but you play the straight man here - in more ways than one. Was that frustrating for you?

No, that was the challenge - having to be funny while playing the straight guy, because there's a lot of wacky stuff going on. Certainly with Nia and Toni, their characters are funny and my guy is not funny. And I thought, "Well, how do I make him funny without playing it funny?" That was a great challenge. You know, there's that insecurity where you're thinking, "Oh my God, I'm the only one who's not funny." But that's actually the funniest part - my playing it straight makes the whole scene funny. As an actor you have to figure out what the whole scene is about, not just your character. But my character is like the audience; I have to be looking at everything like I don't understand it, and just be very sincere. Sincerity can be very funny in certain situations, and that was the key.

Would you like to be doing more comedy?

Well, it's just a script by script process for me. I enjoy comedy and I hope that people enjoy watching me do it. I like funny films, and I feel like I understand them and I can be funny, so I look forward to doing more.

You're next playing the crime writer James Ellroy in My Dark Places. How intimidating is that, given that he's still around, and quite an intimidating person anyway?

I haven't done that yet, but we're trying to get it going. But yeah, it's a tough project. I have met him and he seems OK with me playing him. I very much enjoyed him as a person and I love his writing so... it is daunting, but those are the best things.