Scarlett Johansson's surprise role as the sister in Home Alone sends fans into a frenzy, questioning, "How did I not know about this?"

Fans have gone into meltdown after coming to the realisation that a young Scarlett Johansson features in iconic festive franchise, Home Alone 3.

The Black Widow actress, 39, plays the sister of Alex Pruitt (Alex D. Linz), Molly when she was aged 11.

The third instalment of the festive film series, sees a young Alex take on international terrorist after a microchip hidden in a toy car is mistakenly placed in his care.

Unwell and at home due to chickenpox, Alex spots the unwelcome visitors gauging his miserable neighbour’s – Mrs Hess’ – home, in a bid to find the car and the microchip.

After the thieves realise Alex has been spying on them, they decide to set their sights on the Pruitt home – and the Chicago boy is forced to defend the family home.

Fans have gone wild after spotting Scarlett Johansson playing the sister in Home Alone 3 as they say: ‘How the heck did I not know this?’ (pictured in 1997)

The Black Widow actress, 39, plays the sister of Alex Pruitt (Alex D. Linz), Molly when she was aged 11 (pictured in 2020)

The third instalment centres around Alex, who is forced to protect his Chicago home from terrorist after a remote control car with a hidden microchip is mistakenly placed in his care (pictured clockwise from top left: David Thornton, Alex. D. Linz, Olek Krupa, Rya Kihlstedt, Lenny Von Dohlen)

But fans are also shocked that they failed to recognise Scarlett, who played the indifferent older sister of the protagonist.

Taking to X, formerly known as Twitter, one fan wrote: ‘How the hecking HECK did I not know Scar Jo is in Home Alone 3??????’

‘Holy s***…Scar Jo was in Home Alone?….Wow,’ another added: ‘Scar Jo is in Home Alone 3 and my mind is blown.’

‘How did I just a realize say Scar Jo was the sister in Home Alone???’

‘Bruh I never realized Scar Jo played in Home Alone 3,’ one quipped.

Others were slightly more shocked about the revelation, adding: ‘Scar Jo is in Home Alone 3 and my mind is blown.’

‘HOLY S*** I DIDNT KNOW SCAR JO WAS THE SISTER IN HOME ALONE 3.’

However fans weren’t the only ones who didn’t recognise the Lucy actress – even her own daughter didn’t spot her in Home Alone 3.

Scarlett is completely unrecognisable in the 90s film and fans also seem to agree too (pictured: Scarlett and Alex D. Linz)

Fans went wild after they spotted the young Lucy actress in the festive film

During an appearance on Late Night With Seth Meyers in 2021, the actress shared that they hadn’t intentionally shown her daughter the film, it naturally came on.

She said: ‘Of course, naturally we did Home Alone. And I happened to be in the third Home Alone movie, and so I didn’t say anything to her because I thought she would make a big deal out of it.’

But a then six-year-old Rosie didn’t realise Molly Pruitt was actually her mother ‘right away’, the actress shared.

‘I had to really, like, [say], “See who that is?” She’s [Rosie] like, “Whatever. Is that you?“ I was like, “It’s me, your momma.“ And she was like, “Oh, OK. Whatever“.’

But fans weren’t the only ones who didn’t recognise the young actress straight away – even her daughter, Rosie – then six – took a while to spot her mum