Han, a native of North Korea's capital Pyongyang, had only eight minutes of regulation time remaining when Cagliari coach Massimo Rastelli sent him into the fray during Sunday's 3-2 defeat by Torino.
But that didn't stop him beating England goalkeeper Joe Hart in the fifth minute of injury time, powering home a deft header and wheeling away in celebration.
"I am very happy with my first Serie A goal," Han enthused, revealing his footballing hero is Cristiano Ronaldo.
"I thank the team, the manager and my teammates. I feel at home in Cagliari."