Julianne Moore saved Alicia Vikander from unwanted attention on the set of 'Seventh Son'.

The 57-year-old actress threatened to walk out on the 2014 production after an unnamed man left her co-star feeling uncomfortable with an inappropriate joke at her expense.

Alicia, 29, recalled to the new issue of America's Vogue magazine: ''I was really embarrassed, and I would have just laughed it off.

''But Julianne turned to him and said, 'If you ever do that again, I'm walking out of here and I'm not coming back.' She was just, like, 'Don't you f***ing say that again.' It showed me that she had the power. And that meant so much to me.''

The 'Tomb Raider' actress - who is married to Michael Fassbender - is now using her own power as part of the Time's Up movement and she thinks it is ''really cool'' that the initiative has brought so many actresses together and she can now count the likes of Natalie Portman and Reese Witherspoon as her friends.

She said: ''It was such a community that came together. I got on the phone with Natalie, whom I'd never met, and Reese. Suddenly I felt like I made a lot of new friends.

''One thing that really got to me in their initial email was the fact that -- because women are not as well represented in all industries -- we often have to fight for jobs.

''The competition is so tough that instead of getting to know each other and working together, we learned at an early age to compete for that single spot.

''So then to get on the carpet yesterday and feel like I had actually made friends with the other actresses and people I admire, it was really cool.''