Worli police said the 22-year-old girl had placed order for pizza with Chovisan Pizza Center in the area this evening.
The accused brought pizza to her residence, and noticing that she was alone, he allegedly barged in and tried to rape her, police said.
As the girl resisted and raised alarm, he assaulted her with a kitchen knife and ran away, they said.
The girl lay in pool of blood for quite some time, but neighbours arrived after hearing her cries. She was taken to Poddar hospital.