Emery's men recorded a 2-0 win at the Estadio Ramon Sanchez Pizjuan and the 42-year-old is confident that they can seal the deal in the return at the Mestalla on Thursday.
He told reporters: "Before the first leg I said our chances were 50-50. Now the odds are stacked a bit more in our favour but we must be very cautious and play with a lot of respect for our opponents.
"We are all in a good place, close to something extraordinary.
"We know it's going to be a tough game. We need to continue what we did in the first leg, recognising Valencia's threat and potential. I have faith in our ability."
Emery then went on to stress that he will put his feelings for former employers Valencia aside as he looks to reach the Europa League final with his current club.
"For me to be here again – I can't explain how good those four years were but I am putting these feelings aside," he explained. "I'm not looking to defeat Valencia; I'm looking to guide Sevilla through to the final.
"I've played a semi-final before with Valencia in the Europa League but I lost to Atletico [Madrid]. I have another chance now with Sevilla.
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