Dave Jones rued two defensive lapses that allowed Leeds to beat Wednesday in Saturday’s early kick-off at Elland Road.
Former Owls loanee Luke Varney planted two second half headers to overcome Jermaine Johnson’s opener and secure victory in the Yorkshire derby.
But Jones was unhappy with his side’s defending, saying:
“We’ve let ourselves down today because you can’t allow free headers like that. Whether it was tiredness or just a lack of concentration, I don’t know, but we’ve come away with nothing when we should be taking something home today.
“We’ve played a lot of football in a short period of time and sometimes that can catch up with you. Maybe that has happened to us today.”
Jones had no argument with Varney’s first goal, a header that bounced over the line from the underside of the crossbar.
He said: “The linesman has given it so he must have been sure. That was the decision he made so we will abide by it.”
Owls goalscorer Jermaine Johnson withdrew just after the restart and Jones revealed a knock to the knee dictated the Jamaican’s absence.
Giles Coke also came off injured.
Jones added: “JJ took a kick on the knee and we said to him at half time, just give us what you can and we’ll take it from there.
“But he was feeling it almost straight away so we had to take him off.
“Giles is also injured so we will assess them both tomorrow and see where we are.”