Jason Derulo mocked Liam Payne's girlfriend and son during a rap battle.

The 28-year-old singer went head-to-head with the 'Strip That Down' singer - who has eight-month-old son Bear with 34-year-old partner Cheryl Tweedy - on this week's episode of 'Drop the Mic' and made a number of jibes at Liam's expense, starting with branding him the least popular member of One Direction.

He said: ''Look, everybody! It's the guy from 1D. Not the pretty one, not the gritty one - it's the one you never see.

''Your biggest win is havin' an older woman. But holla at ya boy when you sell a hunnid million.

''Those are some numbers that actually pay. And your first single sounds like one of my throw-aways.''

Liam, 24, hit back at the insult about his girlfriend, adding in a quip about Jason's mom in retaliation.

He rapped: ''Yes, my girlfriend is older, ya ain't wrong. Older women love me, especially your mom.

''Making fun of One Direction, Jason, that's lazy. I got that one D that'll make a lady crazy.

''You're attacking the things that I did as a kid. Made a song called 'Get Ugly,' then you actually did.

''You here to take me out? Well, I wish you good luck. You finally answer the question: 'What if D'Angelo sucked?'''

The 'Talk Dirty' hitmaker went on to mock Liam's penchant for shirtless selfies, insisting the images made his opponent look like a ''clown'' - and he also slipped in his own mom joke.

He rhymed: ''And you take shirtless selfies like you a clown. But I'm the only one that should be strippin' it down.

''This boy right here, he's not worthy to me. But at least I get to tell his mom to talk dirty to me.''

And Jason couldn't resist striking a blow over Bear's unusual name.

He said: ''Your son is Bear Payne, yeah that's cool, I'm sure that will go well with the kids in high school.''

At the end of the rap battle, hosts Method Man and Hailey Baldwin declared Liam the winner.