Brazil's victory included the the quickest goal ever at a FIFA tournament.
After a long ball from midfield was flicked on by Alex into the path of Fabinho, he lobbed the ball over keeper Jacob Gleeson.
The goal was officially timed at nine seconds, beating Hakan Sukur's 11 second strike for Turkey against Korea Republic at Korea/Japan 2002.
Lazaro's strike five minutes later gave Brazil a 2-0 up lead.
Alex finished with three assists and one goal.