James Corden admits he was awestruck by Meryl Streep's spine-tingling vocals demonstrated in Stephen Sondheim's showstopping soundtrack for 'Into The Woods'. And we really can't say we blame him.

Emily Blunt and James Corden in 'Into The Woods'
James Corden and Emily Blunt play the cursed Baker and his wife in 'Into The Woods'

Ok, so we already knew Meryl Streep had some pretty impressive pipes on her following her spectacular performance in 'Mammi Mia!' which, understandably, was then nominated for a Grammy award for Best Soundtrack, but 'Into The Woods' is something else. It's one thing being able to knock out a pop hit, it's another to reach impossible heights in emotional show tunes; co-star James Corden insists she's done just that.

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'We were rehearsing the 'Your Fault' song where Meryl comes in at the end and sings 'Last Midnight'', he explains. 'I thought she was just going to sing the first couple of lines because we were just round the piano, but she just sang the whole thing and I could feel every hair on my body stand up and I was looking at Anna and we were just gobsmacked. I couldn't believe this voice was in there!'

Streep, who plays the Wicked Witch in the stage to film musical,  has other solos including 'Witch's Lament' and 'Stay With Me', the latter of which we have already had a glimpse of in the film trailer - a song which she croons to her adopted daughter Rapunzel.

More: Watch the trailer for 'Into The Woods'

Corden - who plays the cursed, childless Baker in the movie - admits that Streep's voice was so mindblowing, he felt lucky to be getting paid to witness it.  'I remember thinking at the time, if this was an auction prize it would go for millions of dollars', he says. 'To just be round a piano listening to Meryl Streep singing Stephen Sondheim songs. I think people are going to be completely blown away by her performance.'

'Into The Woods' is out on Christmas Day.

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