Scarlett Johansson will ''hand the baton'' to Florence Pugh in 'Black Widow', according to director Cate Shortland.

The 51-year-old filmmaker has explained how the Marvel Cinematic Universe movie will mark a farewell for Scarlett's Natasha Romanoff and will see Florence's alter-ego Yelena Belova move into the spotlight.

In an interview with Empire magazine, Cate explained:

''(Kevin Feige, Marvel boss) realised that the audience would expect an origin story so, of course, we went in the opposite direction.

''And we didn't know how great Florence Pugh would be. We knew she would be great, but we didn't know how great.''

Shortland added: ''Scarlett is so gracious, like, 'Oh, I'm handing her the baton.' So it's going to propel another female storyline.''

Cate revealed that the movie would be a ''fitting'' goodbye for the character after some Marvel fans were upset with the way she was killed off in 'Avengers: Endgame'.

She said: ''In 'Endgame', the fans were upset that Natasha did not have a funeral. Whereas Scarlett, when I spoke to her about it, said Natasha wouldn't have wanted a funeral. She's too private, and anyway, people don't really know who she is.

''So what we did in this film was allow the ending to be the grief the individuals felt, rather than a big public outpouring. I think that's a fitting ending for her.''

Scarlett previously described Florence, 24, as like a ''little sister'' and revealed they developed a close bond on the 'Black Widow' set.

The 35-year-old actress said: ''I don't have a little sister. But with Florence, it feels to me like there are some elements of big sister little sister.''

The 'Jojo Rabbit' star added that she admired Florence's self-confidence.

Scarlett said: ''I wish I was as confident as she is when I was her age.

''She's body confident and has a lot of self-respect.

''She reminded me - just by listening to her talk about relationships with friends, family or her partner - how important it is to have confidence in your beliefs and desires.''