Millwall boss Gary Rowett admitted his team were punished for some terrible defending in their defeat at QPR.
The Lions were beaten 3-2 at the Kiyan Prince Foundation, where they were two up at half-time after goals from Jed Wallace and Mason Bennett.
All three second-half Rangers goals resulted from defensive lapses by the visitors.
Charlie Austin got in front of Alex Pearce to head home Geoff Cameron’s cross before Ryan Woods giving the ball away led to Stefan Johansen equalising.
And worse followed for Millwall when Jordy de Wijs headed in Ilias Chair’s corner four minutes from time.
Rowett said: “In the first half we were excellent. We got to grips with QPR, moved the ball well, had very good chances and took two of them.
“We spoke clearly about maintaining that intensity in the second half. For us to then concede so early in that second half – I thought it was a really poor goal.
“Charlie Austin gets in front of us and for them to score with one ball and one header from quite far out was really disappointing.
“The second goal was equally as poor and for the third we left the man free at a set-piece.”
Two misses by Shaun Hutchinson when Millwall were ahead also proved costly for the south London side.
“You have a glorious chance to take the game away from QPR but you don’t take it,” Rowett said.
“They score quite quickly after that and as soon as they score it gives them a real lift.
“It was a combination of not being able to maintain that energy level and making three really bad mistakes.
“We made mistakes, they punished us and we probably got what we deserved.”