A 75-year-old was beaten so horrifically with his own walking stick that it left a visible imprint on his chest.
The pensioner was left black and blue by thieves, who demanded the man's smartphone before attacking him with the stick and fleeing.
He was shopping in Harrow town centre, north west London, around 8:10pm on Saturday when the assault took place.
His attacker beat him repeatedly around the neck, chest and arms with the stick.
The victim initially went home, but attended hospital later that evening where he was treated before being discharged.
The attacker is described as a white man, possibly aged in his early 20s, who was wearing a baseball cap.