Naomi Watts is feeling under pressure! The Aussie actress admits she’s worried about playing legendary screen siren Marilyn Monroe in a big budget movie.

“I don’t have a plan yet on how to do it,” she said.

“It’s going to be a huge undertaking because everyone obviously has their own idea about who she was.

“It’s a high pressure thing to take on because of how iconic she was. But I’m just not there yet. I don’t know how I’ll go about it.”

Watts — who has sons Alexander, two, and Kai, 1, with long-term partner Liev Schreiber — recently admitted motherhood is the “hardest thing” she has ever done.

“I didn’t ever think I would be having kids this late,” she said.

“Then two under the age of two in diapers — it’s the hardest thing I’ve ever done, but the most rewarding.”