Things get competitive when talented twins Max and Harvey arrive in the music mansion. The singers have to get creative in a music video challenge. The mums try to hold their nerve as they take to the rally track for some high-speed karaoke. And it's the chance for one singer to pull ahead of the pack as we reach the crucial fourth Sing-Off.

The singers have a music master class with song-writer John Newman. Things get emotional in the lesson when the kids take on a powerful Shawn Mendes song. And the mums go head to head with the Hertfordshire Cheetahs, an American football team who definitely don't go easy on them!

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.