In case you haven't heard by now, JK Rowling and Piers Morgan really don't get on.

But the Harry Potter creator has delivered what could be the knock-out blow in their ongoing online argument.

She tweeted a screen grab of an article which sings her praises - and he called her out for "humblebragging".

Except it turns out the words were written by Piers Morgan himself, back in 2010.

Even though he wasn't tagged in the post, it still caught Morgan's attention.

Fans have been enjoying the exchange.

The argument so far

This all kicked off when JK Rowling shared a video of Piers Morgan being sworn at on a US chat show on Friday night.

Morgan then claimed he'd "never read a single word" of Harry Potter.

Rowling hit back, referencing Piers Morgan's support for US President Donald Trump.

Other digs were about book sale stats, of course.

Piers Morgan's son, Spencer, clearly felt caught in the middle - especially as he's got a Harry Potter tattoo.

Harry Potter fan Simon Key, who runs a book shop in London, decided to get involved too and has been tweeting Piers Morgan the entire text to Harry Potter and the Philosopher's Stone.

Since he began, the book shop owner has made some progress and is currently more than 400 quotations in, out of an estimated 32,567.

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