The Ox's sweet strike put England on the road to a thrilling 2-2 draw in the Maracana Stadium.
England keeper Hart said: "He ripped it up when he came on. You can look at all the Brazilian players - a lot of folks talk about their players.
"But Ox has come on, he's 19 years old, and smashes us back in it. You can't ask for more.
"Alex came on at a good time. We didn't play well in the first half but we battled and dug deep and the Ox will appreciate we did a lot of our work so a player like him could come on."