The Spanish club have made a good start to the season domestically but they could only draw away to Belgium club Genk in their first European game which has put a greater importance on the visit of Chelsea on Wednesday night.
Valencia gave an indication of their potential with an excellent first half performance in a 2-2 draw against Barcelona last week but then at the weekend they slumped 1-0 away to Sevilla.
"This is a very big game for us and we need to beat the favourite in the group," said Emery. "I also know that we are in our best form to win this match as we are strong and we will have a lot of support from the fans.
"We will focus on our team but we know about Chelsea and how good they are. They are a great team and they have some important Spanish players there as well. I believe that we can come out on top and I am hopeful it will be an exciting game.
"We play against a side which will be more physical than our last game against Sevilla but we will try and play to our strengths and assert our own style on the game.
"These days we can all see so much football around Europe that there are few surprises and we know a lot about the opposition. Chelsea are a solid side who make few mistakes."
Emery wants to tap into the sense of optimism which has emerged since the draw against Barcelona.
"Everyone said after that match how good we were and then we went and lost against Sevilla. I know the real state of the team and not how it appears from the outside. We need to play our own game and take our chances," he said.
The match sees the return of Juan Mata following his summer move and former-teammate Ever Banega admitted that while friends off the pitch they will put that aside for the duration of the game.
The 23-year-old moved to Stamford Bridge in August and is the latest big money buy for the English giants as they continue their Champions League quest.
"He's a fantastic player and we miss him but we have to continue without him. We have other players who have been able to replace him and on the pitch he is an opponent," said Banega.
"It will be a difficult game especially after what happened in the first leg and all we can do is be as well prepared as possible."
Source: AFP
Source: AFP