Emergency services found the man had allegedly been stabbed after they were called to a fire at the home on Inglis Street in Grange just before 5.30am.
Neighbours and a passerby called 000 after being woken to the sounds of screams.
Firefighters arrived to find a curtain of fire inside the brick home.
The man, who police say had suffered “an apparent stab wound”, was rushed to hospital with critical injuries.
A crime scene has been declared at the home and a woman, who is known to the man, is speaking with police.
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A neighbour of the home has told Today the incident is shock for the “very quiet street”.
“Nothing happens in this street,” Tegan Sprenger said.
She said the young man who lived at the home had lived there for a while and seemed “like a nice guy”.
Anyone with information about the incident is urged to contact police.