Tulisa and Alan Sugar in X Factor Twitter war
Alan, 65, tweeted: "Can you tell me who the hell this bird is on X Factor. What has she done?"
He added: "This Tulisa talks nonsense on X Factor, what qualifications does she have to judge singing talent."
X Factor judge Tulisa replied: "@lord_sugar as someone that came from nothing to something maybe u should have more respect for people that have done the same.
"I have grafted from the age of 11 with my band NDUBZ, we wrote & produced all our music, sold 3 platinum albums, 3 sell out tours the last being an arena tour & a No.1 debut solo single!
"So mr lord of judgement... stick to judging the Apprentice & I'll stick to what I know MUSIC. #itsaNOfromme."
She then apologised to her 2,258,202 followers for her outburst: "Soz bout that peeps. But that t*at has been bad mouthing me since last year!"
But Lord Sugar proved he's not intimidated by Tulisa's feisty attitude and was determined to have the last word.
He replied: "Don't insult me by comparing my humble beginnings with yours."
Lord Sugar is known for his snappy, no-nonsense Twitter attitude and is embroiled in an amusing online war with journalist Piers Morgan.
Piers picked up on Alan's latest argument and Tweeted: "Oh dear... @Lord_Sugar getting schooled by @officialtulisa - most amusing."
But Alan retorted: "@piersmorgan shut up... you have as much talent as her."