Despite the Swede's moment of inspiration, Lecce were able to fight back to draw 1-1.
"Ibrahimovic scored an extraordinary goal and took everyone by surprise," said Rosati.
"Nobody expected him to bring out a shot like that in those circumstances, but that's why he is a champion."
Milan coach Max Allegri added: "We try to make the most of Ibrahimovic and his qualities. He scored a fantastic goal today."