Jennifer Hudson joins a cappella group Pentatonix for a rendition of the traditional song 'How Great Thou Art' as part of their forthcoming NBC special 'A Very Pentatonix Christmas', which is named partly for their festive album of the same name out now as a deluxe edition.

Jennifer Hudson at the ITV galaJennifer Hudson at the ITV gala

The 36-year-old singer appeared on the Texan group's re-release of their 2016 Platinum-certified number one 'A Pentatonix Christmas'. The deluxe version, which dropped in October, also includes other traditional songs - 'Deck The Halls' and 'Away In A Manger' - as well as 'Let It Snow! Let It Snow! Let It Snow!' and a second version of Leonard Cohen's 'Hallelujah' featuring The String Mob.

Pentatonix will be performing a TV special next week to celebrate the holidays, a performance which also features new bass vocalist Matt Sallee who will be touring with the group throughout December. 

The group also have dates at the Chicago Theatre, Tower Theatre in Upper Darby, Pennsylvania, Mohegan Sun Arena in Uncasville, Connecticut, Wang Theatre in the Boch Center in Boston, The Anthem in Washington DC and Beacon Theatre in New York City.

Earlier this year they also released their 'Ptx Vol Iv: Classics' EP. But Pentatonix have become well known for their Christmas efforts; their first holiday album was 2012's 'PTXmas' (plus the following 2014 deluxe edition), and they properly broke out with 2014's 'That's Christmas to Me' featuring the amazing 'Winter Wonderland' / 'Don't Worry Be Happy' medley with Tori Kelly.

This year the group have already been nominated for Favorite Music Group at the Nickelodeon Kids' Choice Awards and a Daytime Emmy Award for Outstanding Musical Performance in a Daytime Program following their 'God Rest Ye Merry Gentlemen' appearance on Rachael Ray. They also won the Grammy for Best Country Group Performance after performin 'Jolene' with Dolly Parton.

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'A Very Pentatonix Christmas' airs on NBC on November 27th 2017.