Celebrity interview - George Clooney and Renée Zellweger

Hollywood hunk George Clooney and Bridget Jones actress Renée Zellweger star in Leatherheads, currently showing at the cinemas. Sarah O'Meara talks to the stars about the fun they had making the rom-com.

Even wearing four-inch, black patent Christian Louboutin heels (the ones with the red soles) Renée Zellweger is still half a head shorter than her Leatherheads co-star and director George Clooney.

But as the two discuss his homage to the 1940s' screwball comedy - think witty banter, Bringing Up Baby, Howard Hawks, raised eyebrows and cloche hats - what the Texan tinkerbell lacks in size, she makes up for in "verbosity", as she calls it.

According to Mr Clooney, Ms Zellweger's natural wit and sarcasm, often disguised by her breathy, southern tones, made her the obvious choice for his latest directorial effort.

"We slur. We say 'you know'. But Renée has this incredible ability to walk straight into a period piece," he says admiringly.

In his first directing venture since Good Night And Good Luck, Ms Zellweger plays Chicago Tribune reporter, Lexie Littleton, on the trail of top football star Carter Rutherford (John Krasinski, from the American version of The Office).

Dressed to kill, she is more than a match for any man, and crosses verbal swords with wise cracking football manager, "Dodge" Connolly (Clooney) at every opportunity.

Set in the late 1920s, Leatherheads charts the rise of professional American football. Seen as a game for losers with nowhere else to go after high school, Dodge sets out to change things.

He persuades American college football star and decorated war hero Rutherford to join his team, the Duluth Bulldogs. Soon the players are wearing fur, the stands are packed and sponsorship deals start flooding in; but Lexie has her doubts about Dodge's star player.

Mr Clooney and Ms Zellweger are natural sparring partners, both on and off screen. Speaking about the film, Mr Clooney waxes lyrical about his love of 1940s comedies, citing directors Frank Capra and Howard Hawks as major influences - while Ms Zellweger admits to knowing exactly nothing about the genre.

She says: "I just liked the script. Coming from George, believe it or not, it really was good. I'm completely ignorant of cinema history and this fella here had to educate me a little bit. We had screenings in place of rehearsals most of the time, just to make sure everyone was familiar with the style of the time. It was a challenge. And I didn't want to get hit so I did my homework."

Mr Clooney clarifies cheerfully: "I never did it with a closed fist - always the open hand."

It's hard to stay serious with these two in the room. Ms Zellweger is as coy, mischievous and irreverent as Mr Clooney is passionate, good-humoured and frank. As the conversation wheels from curling to politics, every opportunity to mock one another is taken.

Mr Clooney has spent the morning at Downing Street with Gordon Brown discussing the violent conflict in Darfur, a region of the African country of Sudan. As a UN peace envoy he is pushing for peace talks and further funding.

"We're not going to invade a Muslim country to solve its problems; we've done that, with not great success. It's a very complicated issue. Gordon was amazingly helpful. He suggested that London be a place where the rebel leaders could meet."

As Mr Clooney talks about funding initiatives led by Mr Brown, which could buy much-needed helicopters to transport UN forces around Darfur, Ms Zellweger gives him her full attention. But although she is clearly smitten by his political conviction, both actors have always claimed to be just good friends.

Mr Clooney says: "I was joking in an interview and I said something like, 'Well I like her a little bit'. And the next day it was all over the papers. She came in and was like, 'Just a little bit?!' Jokes don't work often in print."

Commenting on his reputation as a women magnet, Mr Clooney puts his sexual allure down to his hair. "I have good hair - which I just bought." Ms Zellweger quips: "It looks almost natural." No. She's clearly not auditioning for the much-coveted part of Mrs Clooney.

But their lack of sexual chemistry off screen doesn't stop sparks flying on set. A series of gorgeous suits and dresses, artfully created by Mr Clooney's favoured production designer Louise Frogley, make Ms Zellweger fairly irresistible and even manage to give the svelte beauty a few curves. Up close, Mr Clooney is more likely to be accused of being on the thin side. His weight loss during filming prompted rumours of cancer, but can apparently be attributed to too much exercise. Now in his late 40s, he admits directing and acting in a football movie was a challenge.

"I put all these old man jokes (into the script) because it was a project I was looking to do 10 years earlier, when I would have been about the right age to be 'too old to be' playing football.

"At 46 you get hit and it hurts. I'd look at the monitor after a take and be like 'I think we got it' and Grant the producer would say, 'Go back out there and shoot it again'. The first few days I was running 100-yard dashes back and forth and thinking, 'It's only 65 more days of this'."

But despite such self-deprecation, Mr Clooney admits that as a teenager he had two try outs for baseball team the Cincinnati Reds.

"I only lacked talent. The rest of it I had," he deadpans.

Still a keen sports fan, he likes watching college basketball which he loves for its focus on team spirit rather than money. "I think it's the most fun time in sports," he says.

Ms Zellweger, on the other hand, "has a thing about cricket". But she confesses in her sweet drawl that she hasn't got a clue what's going on. "I just like those guys in their little white outfits, very nice, thank you. But don't tell Hugh Grant I don't know a thing about cricket. He will end the friendship immediately."

Listening to the pair's incessant banter, you get the sense that working on this film together was a genuine pleasure. Was this the real reason Mr Clooney suddenly decided to do a romantic comedy?

"After Good Night And Good Luck and Syriana every film I was sent to direct was an issue driven film," he says. "I wanted to do a comedy but if you're going to do a romantic comedy, it's about housing it in something we haven't seen before. I spent a summer working on the script in Italy, with Renée in mind to do the part. It's easy to write when you have someone as talented as Renée in mind for it, so that was part of the fun."

So what you're saying Mr Clooney, is that you spent a summer at your romantic villa near Lake Como thinking about Ms Zellweger? Yep: clearly just good friends.