LUCY LIU was looking to make a TV comedy.

"I adore doing comedy," says the 44-year-old Liu, whose breakout series Ally McBealled to high-profile movie roles in the likes of Charlie's Angels , Kung Fu Panda and Quentin Tarantino's Kill Bill .

What Liu got instead was a topless Jonny Lee Miller doing push-ups while she attempts to focus on her lines.

"Yeah, I'm pretty good at being focused," Liu says with a laugh. "And we do it so many times … we're with each other so much. Luckily we really do get along. We haven't gotten sick of each other yet."

Liu is Dr Joan Watson to English actor Miller's Sherlock Holmes in Elementary, a modern spin on the classic detective story.

Now in its second season, Elementary looks set to be a long-runner for Liu, after her previous few series - Southland, Dirty Sexy Money and Cashmere Mafia - came and went within one or two seasons. A third season has yet to be locked in, but all signs from US network CBS are "encouraging," says Liu. Strangely, she's finding such positivity a little unnerving.

"It's so strange because as an actor you don't really live by any kind of schedule, because you could be cancelled at any minute. That would be normal. Like getting a call to say, 'You're on the plane to go to Australia to do this movie for six months' - you just do it! So the fact we have any semblance of a season put together right now is shocking for me."

Elementary has also allowed Liu, who turns 45 in December, to re-root herself in her home town, New York.

"It's weird to be in this business and know where you're gonna be until a certain time. That's nice but it's also terrifying, because we're so used to being unplanned about our lives. It really changes your format of living. I've gotten a lot out of it."

Elementary wasn't always such a sure bet: initially it seemed it might be the poor American cousin to the BBC's acclaimed Sherlock, starring Benedict Cumberbatch and Martin Freeman as the detective and his sidekick.

But the US series has carved out its own audience and its own brand of Holmes and Watson interplay.

"We still have very strong procedural aspects to the show every week, but our relationship, I think, is what people tune into," Liu says. "What I find the most interesting about the show is how our relationship develops, regardless of what crime we're solving. That's really lovely."

Liu's Watson initially began working with Holmes as his "sober companion" - a well-paid babysitter whose task was to keep him away from drugs. But the eccentric sleuth has now come to count on Watson as a friend and crime-solving partner.

Liu is relishing Joan's evolution.

"I like that she's incredibly patient, she's very curious and she's able to change her life, even though it's against all odds. She's still caring about people but on a much more heightened level, in crime-solving. It's obviously a little more exciting than being a sober companion … or maybe not! It depends on who you have as a companion," she laughs.

At the beginning of this season, Joan finally revealed to Sherlock the trauma that led her to abandon her medical career.

"That was probably one of the heaviest moments she has had," says Liu.

"It's been a big question mark - what happened to her? Why did she get kicked out of the field? It was an important story point for the audience to understand how she fell into the path that she has with Sherlock. Joan has a lot of lighter moments so it's nice to be able to hinge that with this other side."

Indeed, while it may not be the straight up sitcom she was looking for, Elementary allows Liu plenty of comedic opportunities, along with elements of drama, crime and the odd kick-butt moment.

It's enough, she says, "that I don't feel I've lost out on not doing a comedy".

ELEMENTARY

SUNDAY 8.30PM, TEN