Carlos Carvalhal says there is plenty left in the Hillsborough tank following the setback against Reading on Friday night.
The Owls went down 2-0 to the Royals, with an outstanding performance from goalkeeper Ali Al Habsi ensuring the points went the way of the visitors.
But Carvalhal insists his side will return from the international break stronger and remains hopeful that the injury bay will clear for the home straight.
He said: “This has been one of the hardest weeks of my career. We have already lost key players and this week we lose another one with Ross Wallace.
“But still the players did fantastic tonight and I am proud of them, proud of the club and proud of the fans, who were amazing from the first whistle to the last.
“Everyone who sees that game can see that we should have won comfortably but somehow we lose 2-0. It is unbelievable.
He added: “But this can happen in football. The goalkeeper was fantastic on the night, we had seven or eight chances but could not put the ball in the net.
“This was the difference tonight and what we spoke about in the dressing room was coming back stronger.
“We have the belief and during this break I am hopeful some players will recover and be ready for our last eight games, which will be finals.”