Mendes believes they cna knock the Toffees out of the Europa League when they meet for the second leg tonight.
Everton won the first leg 2-1 at home at Goodison Park.
Mendes said: “We can eliminate Everton. This will not be easy, but we achieved a good scoreline in England.
“We need one goal, but that would change the game. It is possible to score in 90 minutes, although, personally, I would like to score early on.
“This Sporting team is not inferior to Everton. We know our rivals and it is possible to exploit the key points in their team.”
He added: “The morale in the squad has increased and we think it is possible to go very far in the competition.”
