The Primera Division outfit ran out 5-1 winners when the sides went head to head at the Mestalla two weeks ago, lifting Los Che to second spot in Group A - three points clear of third-placed St Gallen and one point behind leaders Swansea.
Valencia will be favourites again for Thursday's rematch at the AFG Arena, but Fuego is taking nothing for granted.
"Our aim is to finish top of the group," he said to www.valenciacf.es. "We started this competition badly (3-0 home defeat against Swansea), but we reacted just in time.
"We want to have consistency with our results in Europe but just because we won against them easily it does not mean we will automatically win again.
"We need to show the same focus and make the most of our chances.
"To take a positive result at St Gallen would allow us to take a big step towards qualifying and contend for top spot in the group."
Sunday's 1-0 triumph at Getafe ended a three-game losing streak for Valencia.
The victory eased the pressure on coach Miroslav Djukic and lifted the Mediterranean outfit to ninth in La Liga.
St Gallen warmed up for the encounter with a 3-0 success at Lausanne on Sunday which halted a five-match winless run in all competitions.
The result saw Jeff Saibene's team climb to fourth in the Swiss Super League table, four points adrift of leaders Basle.
Forward Roberto Rodriguez is hoping his team learned lessons from the defeat in Spain and will cope better this time around.
"It will be another game at our stadium, with our fans behind us," he said. "We want to show we can play another type of football and we will go out to attack."
The visitors will be without injured full-backs Joao Perreira and Andres Guardado.