Carlos Carvalhal said the Owls needed to show more killer instinct in front of goal after his side lost 2-1 to Reading at the Madejski Stadium.
Wednesday had chances to take the lead before a deflected effort from Roy Beerens found its way into the back of the net.
Beerens doubled the Royals’ lead before a stoppage time header from Steven Fletcher got the Owls on the scoresheet.
Carvalhal said: “We have chances to score but we didn’t take them, Reading scored without having a real chance before, and this is the difference.
“I don’t remember Keiren Westwood having anything to do for most of the game, but this is football.
“We played well and I am proud of my players but obviously disappointed with the result.
“We have created a lot of chances, we started the second half very, very well but they must be taken.”
On a positive note, young striker George Hirst made his league debut for the Owls when he came off the bench in the second half.
The head coach added: “George did well when he came on.
“He tried to make an impact with his colleagues when he got on the pitch.
“It wasn’t an easy game for him to come into, but he did well.”