The American rapper started a war of words with the 'Smile' singer last night (11.07.13), when Azealia accused Lily of having a drug habit and declared her husband Sam Cooper looks like a ''thumb''.
The vicious spat kicked off when one of Azelia's fans forwarded her one of Lily's tongue-in-cheek tweets from April 2012.
It read: ''YOURE ALL JUST JEALOUS CAUSE IM SOOOOOOOO FUCKING BEAUTIFUL AND HAVE SUCH A PRETTY FACE. (sic)''
Azelia took offence to the comment, and tweeted: ''Weak. She can't talk though. Not when I met her coked up at yoyo ... And NOT with that ugly husband she has. (sic)''
Lily appeared to want to let the comment lie, until Azealia bit back, writing, ''Your husband looks like a thumb''.
The unprovoked attack on Sam - who wed Lily in June 2011 - unleashed the wrath of the 28-year-old singer, who slammed Azealia's music.
Although the rapper - who has insulted Rita Ora and The Stone Roses on the social networking site in the past - has been around for a while, she is yet to release her first album.
Lily scoffed: ''Not even gonna @ her but if she wants to talk about weak , I'm sure her record sales to date should suffice. One hit wonder.
''And my husband ? Don't go there bitch Or your totally unnecessary security detail may actually have something to worry about #wannabe (sic)''
Azealia, 22, replied: ''LOL ill be a one hit wonder but you have ugly children and a coke habit..... Shhhhhhh. #SHUTUP (sic)''.
Nevertheless, the feud was quickly quashed when Lily jokingly added, ''Ps we all need thumbs'', before signing off Twitter for the night after posting a picture of her roast dinner.
He also slapped a jet-lagged Taylor Hawkins.
The acclaimed performer had just cancelled touring due to a battle with cancer.