The Portugal international has voiced his satisfaction with his side's win, but feels that anything can still happen in the return leg
The Lisbon giants went two goals up via Rodrigo and Luisao before Christian Eriksen pegged one back, but again Luisao made sure Benfica returned to Portugal with a two-goal lead.
"It is still a dangerous result for us," Amorim told SIC after the final whistle.
"Tottenham have some great players who have the quality to do in the return what we did here at White Hart Lane.
"One of our biggest strengths is our quick transition from defence to attack and we managed to score three goals here.
"It is very important in knockout games to score in away matches."
The return takes place at the Estadio da Luz next Thursday.