A woman is expected to face an upgraded charge of murder after the man she allegedly stabbed in the heart in Sydney’s south died in hospital, police say.

Police were called to a home on Hannans Road at Riverwood about 11:45pm on Sunday where they found a 39-year-old man, who police believe was the woman’s partner, with a severe stab wound to his chest.

He was taken to St George Hospital where he underwent surgery, but died on Wednesday night about 8:30pm, officers said.

Qian Liu, 34, was arrested at the house at the time of the alleged stabbing and charged with wounding a person with the intent to cause grievous bodily harm.

Police said it was anticipated the charge would be upgraded to murder when Liu appeared in court tomorrow.