Wednesday boss Carlos Carvalhal gave Charlton full credit for their victory and felt it was a game too far for his side as the Owls lost 3-1 at the Valley.
The Addicks stunned in-form Wednesday with goals from skipper Johnnie Jackson, striker Simon Makienok and Reza Ghoochannejhad.
Fernando Forestieri pulled one back but it merely proved a consolation as Carvalhal's side fell to their first defeat since September 12.
"Congratulations to Charlton, they deserved to win," the Portuguese said.
"We have played a lot of games with high intensity, for example against Arsenal, and we have kept four clean sheets but we did not have the energy.
READ MORE: Match Report - Charlton 3 Owls 1
"Charlton played with high intensity and we could not match their style.
"We lost players with injury through the game because their bodies could no longer take it and it meant it was not our day.
"It was not about complacency, it was about the lack of energy. Players could not deal with it. It can happen.
"No one can control this kind of thing. It was a bad day for us but congratulations to Charlton.
"We need the international break and we need to find out how (Glenn) Loovens, Jack Hunt, and Barry Bannan are. We expect to be back at full strength by next week."