Just a few weeks ago, Justin Bieber threw a major diss at The Weeknd by calling his music 'wack' (i.e. crap) - largely because Abel Tesfaye aka The Weeknd is dating his former girlfriend, Selena Gomez.

Now, it seems that the Biebs is going out of his way to slag off his fellow musician, as the latest video displays.

The Canadian pop star was taking part in a live video on Instagram with a friend, and when asked what his favourite song of the moment, he answers 'Starboy' before laughing uncontrollably and saying 'We gotta end it, yo - that was too funny' as the screen goes blank.

Justin, dear, didn't your mammy ever teach you that passive-aggressive bullying is not nice?

Watch it below: