The evidence was sufficient to establish serious injury where the defendant had a three-inch knife during the assault; the victim bled “a lot” from his wounds, dripping blood throughout the bedroom, bathroom, and kitchen; the victim was on the floor in pain and spitting up blood when the officer arrived; the victim was stabbed or cut 8 or 9 times and had wounds on his lip, back, and arm; the victim was removed by stretcher to the emergency room, where he remained for 12 hours, receiving a chest tube to drain blood, stitches in his back and arm, and was placed on a ventilator because of a lung puncture; the victim received pain medication for approximately one week; and at trial the victim still had visible scars on his lip, arm, and back.