Benfica midfielder Manuel Rui Costa has told skysports.com of his disappointment that he will miss the UEFA Champions League clash with Celtic.
The gifted attacker made a playing return for Benfica last Monday, but aggravated an old complaint and has been ruled out for a month.
Rui Costa and his Benfica paymasters are unhappy with the diagnosis they received when the player picked up his initial injury.
"I am very unhappy about this," Rui Costa told skysports.com. "It is in our interests to play and aid the team.
"Now it is necessary to recover properly from this injury.
"I wanted to play in this match with Celtic, it is key for us. If we want to qualify for the next round, we must get a win.
"Throughout my treatment I have dreamed of playing in this game with the Scottish side, it was an important date for me and I am upset I am injured.
"The match against Celtic is of huge importance, a defeat would be terrible as with one point out of nine we would need a miracle to reach the last 16."
Even though he will be on the sidelines, Rui Costa is convinced Benfica have the quality to see off Celtic.
"We are not inferior to Celtic," he stressed. "But the team head there under real pressure.
"If I was asked to analyse the two teams, I have no doubts. Man for man, Benfica have more quality.
"We have greater attacking quality, Celtic have physical power and this is the key to the match."