Valencia's worst fears have been realised with goalkeeper Diego Alves set to be sidelined for at least six months with a serious right knee injury.
The Brazil international was hurt during his team's final game of the season, a 3-2 triumph at Almeria on Saturday, and will have to go under the knife.
A statement from Valencia read: "Tests done have confirmed that Diego Alves has a torn anterior cruciate ligament and a torn external meniscus in his right knee.
"The player will have to undergo surgery."
Alves, who was set to play for Brazil at the Copa America next month, is expected to be sidelined until November.
The 29-year-old will miss the start of the 2015-16 campaign and the preliminary round of the Champions League.
Saturday's victory ensured Valencia finished fourth in the Primera Division standings to clinch the last qualifying spot for Europe's elite club competition.
Alves, who joined Los Che from Almeria in 2011, has kept 13 clean sheets in 37 league appearances for Valencia this season.