She only recently resolved her long-running feud with Katy Perry, but it looks like Taylor Swift may have another new entry on her List of Enemies.

Make that two new entries, actually - since both Justin Bieber and his manager Scooter Braun are involved in this latest dispute.

It all began yesterday, when news broke of the sale of the Big Machine Label Group, a group of independent record labels that specialises in country and pop music. Previously owned by former DreamWorks exec Scott Borchetta, it was sold for a whopping $300 million - and the buyer was the aforementioned Braun.

How does Taylor Swift factor into this? Well, her first six albums were released via Big Machine, which means that Braun now owns them. And she's not one bit happy about that fact. Like, 'steam coming out of her ears' not-happy.

Calling the sale her "worst case scenario", she posted a note on social media accusing Braun of "incessant, manipulative bullying" for years. "Like when Kim Kardashian orchestrated an illegally recorded snippet of a phone call to be leaked and then Scooter got his two clients together [Kanye West and Justin Bieber] to bully me online about it. Or when his client, Kanye West, organized a revenge porn music video which strips my body naked. Now Scooter has stripped me of my life’s work, that I wasn’t given an opportunity to buy. Essentially, my musical legacy is about to lie in the hands of someone who tried to dismantle it.”

You can read her note in full below:

However, that wasn't the end of it - as now Bieber has weighed in on the matter with an Instagram post of his own, defending Braun's honour.

Bieber initially apologised for the 'hurtful Instagram post' that he made around the time of her spat with Kanye West. He then wrote: "What were you trying to accomplish by posting that blog? seems to me like it was to get sympathy u also knew that in posting that your fans would go and bully scooter."

He added: "I’m sure Scooter and i would love to talk to you and resolve any conflict, pain or or any feelings that need to be addressed. Neither scooter or i have anything negative to say about you we truly want the best for you.

"I usually don’t rebuttal things like this but when you try and deface someone i loves character thats crossing a line.."

View this post on Instagram

Hey Taylor. First of all i would like to apologize for posting that hurtful instagram post, at the time i thought it was funny but looking back it was distasteful and insensitive.. I have to be honest though it was my caption and post that I screenshoted of scooter and Kanye that said “taylor swift what up” he didnt have anything to do with it and it wasnt even a part of the conversation in all actuality he was the person who told me not to joke like that.. Scooter has had your back since the days you graciously let me open up for you.! As the years have passed we haven’t crossed paths and gotten to communicate our differences, hurts or frustrations. So for you to take it to social media and get people to hate on scooter isn’t fair. What were you trying to accomplish by posting that blog? seems to me like it was to get sympathy u also knew that in posting that your fans would go and bully scooter. Anyway, One thing i know is both scooter and i love you. I feel like the only way to resolve conflict is through communication. So banter back and fourth online i dont believe solves anything. I’m sure Scooter and i would love to talk to you and resolve any conflict, pain or or any feelings that need to be addressed. Neither scooter or i have anything negative to say about you we truly want the best for you. I usually don’t rebuttal things like this but when you try and deface someone i loves character thats crossing a line..

A post shared by Justin Bieber (@justinbieber) on

Braun himself has yet to comment on Swift's post, but we have a feeling this one could run and run...