The singers get a taste of what it's really like to be famous when they face a tricky interview at Radio 1. Which one of them will dish the dirt when DJ Maya Jama tries to dig a little deeper into their personal lives? Then it all falls to pieces in the music lesson when the singers take on an Ariana Grande track, which proves to be their biggest nightmare. And it's time to find out which of the mums knows their child best when they are entered into in a game show challenge with a very messy forfeit.

Things heat up when the arrival of Olly Murs causes a music mansion meltdown. The singers struggle to sing in Spanish when they take on a Liam Payne track. It all goes downhill for the mums when they are chased by a yeti down the UK's longest toboggan track. And one singer finally pulls ahead of the pack in the all-important seventh Sing-Off.

Things get emotional for one singer when the group take on a Spanish dance challenge. It all gets a bit cringeworthy when the mums take to the stage in a lip-sync battle. And in the final sing-off, one singer walks away with the elusive fast pass into the grand final.