Charlize Theron says the sex scene in 'Long Shot' is short because she was ''tired that day''.

The 43-year-old actress plays Charlotte Fields in the comedy, the US Secretary of State and presidential candidate who embarks on an unlikely relationship journalist Fred Flarsky (Seth Rogen) who she used to babysit.

One sex scene in the movie shows both characters climax in a matter of 10 seconds and the 'Monster' star has now revealed that she ''went for comfort'' during shooting and didn't feel like ''doing all the work'' that comes with filming a long sex scene.

Speaking to Vulture at a screening of the film in New York, Charlize said: ''I'm gonna be honest with you. I was tired that day. I didn't wanna do all the work. I went for comfort!''

Seth added: ''Which is a lot like real sex!''

The scene has drawn criticism since it premiered at South by Southwest, with Mashable's Angie Han commenting that the film lacked realism regarding women's sexuality.

Seth previously responded to this criticism on Twitter, explaining that it was actually the 'Atomic Blonde' star's idea to make the scene so swift and admitted he too had initially expressed doubt.

He wrote: ''Believe me, I had my doubts and Charlize demanded it was possible much to the shock of myself and director. We went with her suggestion.''

Charlize previously praised her co-star Seth insisting she has always been a ''fan'' of the 38-year-old actor and all his movies so was delighted to work with him in the comedy.

She said: ''I've been a sincere, down to the core of my body, fan of Seth Rogen's. I have watched everything that he's touched and never in a million years did I think I would be in a movie with him, so I am hashtag blessed.''