Naomi Watts binge watched 'Game of Thrones'

Naomi Watts says she had not seen "Game of Thrones" before she gave a nod to starring in its spin-off, but finished the HBO series in three months after she was "hooked" to it.

The actor, who is set to headline the much-anticipated prequel of the epic fantasy show, said her brother, photographer Ben Watts egged her on to watch it.

"I didn't start watching until I was approached about this job. But my brother, who is heavily into it, told me, 'Under no circumstances are you going to turn this down'," Watts told Net-A-Porter's PorterEdit magazine.

She added that as soon as she started watching "GOT", she "was in - hook, line and sinker".

The 50-year-old actor said she now has a better understanding of the show's fandom and has an idea on how important her stint in the spin-off could have on her career.

"I still have fears about that. I don't really know what to prepare for," she added.

According to HBO, the new show will be set thousands of years before the events of "GOT".

It will chronicle the world's descent from the golden Age of Heroes into its darkest hour. From the horrifying secrets of Westeros's history to the true origin of the White Walkers, the mysteries of the East to the Starks of legend, the official logline of the show read.