Police arrested a homeless man who injured a 3-year-old Brooklyn boy when he threw a beer bottle during a fight with another man that accidentally struck the child, police sources said.

Jorge Cayetano, 33, and another man had just bought beer from a Sunset Park supermarket when they got into a fight that spilled out onto the corner of 5th Avenue and 60th Street around 9 a.m. Tuesday.

During the melee, Cayetano chucked his 22-ounce bottle of Olde English at his rival, missing the man and striking little Alex Li in the face.

The two drunks scattered, leaving the boy bleeding from a deep gash above his right eye.

Li was stitched up at nearby Lutheran Hospital.

Cayetano was arrested Wednesday. He had not been charged as of Wednesday afternoon.