Substitute Silva believes the game will prove to be a turning point for a team who dominated their first two games against Iceland and Austria, but had to settle for a draw each time.
"We are not losing sleep but we are saddened," Silva told a news conference on Monday. "No one is going to throw in the towel. We will bounce back to reach our goal. I'm confident.
"We don't deserve to be in this position. You are left with a bitter taste because your work has not been rewarded but the fighting spirit and the confidence of the group are still intact."
Portugal had 10 attempts on target against Iceland for a 1-1 draw and against Austria, they managed six but failed to score.
"The only issue is that the ball is not going in," Silva said. "Unfortunately, we have been unable to finish off the numerous chances we have produced."
Portugal captain Cristiano Ronaldo has yet to hit the back of the net.
Ronaldo, who scored 51 goals in 48 games in all competitions for Real Madrid this season, missed a late penalty against Austria.
"If we didn't create chances, we should have reason to be worried," said Silva.
"Just because we haven't achieved the best results, it doesn't mean that everything is bad. But I am sure things will change."
(Writing by Adriana Garcia, editing by Julien Pretot)
