Emery spent four years as coach at the Mestalla between 2008-12, leading them to three consecutive third-place finishes in La Liga and the 2011-12 Europa League semi-finals.
On that occasion, Emery's Valencia were vanquished by eventual winners Atletico Madrid, but his hopes of reaching this season's showcase are boosted by a 2-0 first-leg win in Seville.
Valencia reached the semi-finals thanks to a stunning turnaround against Basel, winning 5-3 on aggregate, despite a 3-0 first-leg loss in Switzerland.
And Emery remains wary of his former club's capacity to spring a surprise at the Mestalla on Thursday.
"For me to be here again – I can't explain how good those four years were, but I am putting these feelings aside," he said.
"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. I have another chance now with Sevilla.
"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.
"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."
'People will remember us because we got to No.1 in the world rankings and achieved great things - but our biggest regret is that we didn’t win anything': Ex-Everton star Kevin Mirallas opens up on 'honour' of being part of nation's golden generation
‘I’m sure we’d have finished in the top four or five if he hadn’t joined Chelsea in January. Him leaving damaged the team, but we couldn’t stand in his way’: Alan Curbishley reflects on failed Champions League dream after selling key player
