Chris Powell urged his Charlton side to be more clinical or risk suffering more defeats like the 2-1 reverse to 10-man Watford at The Valley.
The Addicks dominated for large periods of the contest and created a string of chances but had only Ricardo Fuller's equaliser to show for their efforts after Tommy Hoban had opened the scoring for the visitors.
The Hornets had Fernando Forestieri sent off shortly after the restart but still ran out unlikely winners thanks to Almen Abdi's 70th minute strike.
"I always knew it was going to be tough," said Powell. "That is just how this league is.
"It is unforgiving and we have been hurt by two set plays. I think Ben Hamer only had two saves to make and we've lost the game.
"We've had 15 chances but only taken one so you have to try and be as clinical as you can.
"It is going to be a tough old season, no doubt about it. There will be a few ups, a few downs but you've just got to keep going."