An ice addict who admitted fatally stabbing his ex-lover's father in the heart after threatening attacks will be sentenced in Brisbane.
Mitchell James Sayers was initially charged with murder over the December 2015 killing of Ian Robert Jones.
But on Tuesday, the second day of his Brisbane Supreme Court trial, he unexpectedly pleaded guilty to the lesser charge of manslaughter.
During a hearing, Mr Jones' daughter Carmen Jones said Sayers' selfish attack on her dad had robbed his children of a great father and had made every day a struggle.
Sayers killed Mr Jones during a scuffle outside the 54-year-old's Marsden unit, with the court hearing he drove a blade 12-18 centimetres deep into the older man's chest, hitting his heart.
Mr Jones died instantly.
Justice Martin Daubney will sentence the 28-year-old on Friday afternoon, with the court on Wednesday hearing he should be jailed for at least eight years.