Leeds chairman Ken Bates is hoping Tuesday night's chastening 5-2 defeat to Barnsley can spur Simon Grayson's side onto further progress in the Championship.
The Whites have impressed since their return to the second tier and were sitting in the play-off places with 10 points from five games ahead of the Oakwell debacle.
"It was a great disappointment and an eye-opener because if we'd won we'd have been up with the big boys," Bates told Yorkshire Radio.
"It appears we just collapsed, but given the timing, perhaps it's a good thing in that it could be an alarm call for anyone who though we were going to walk through this division.
"The fact of the matter is that we took nearly 7,000 fans who were singing and cheering and our players need to look in the mirror and ask themselves a few questions.
"On the other hand it was a day a lot of big clubs got beaten. Norwich, Cardiff and Burnley all lost and the biggest shock of the night was managerless Scunthorpe United going to Sheffield United and giving them a trousering."