Grant McCann's injury-time volley secured a glorious Peterborough United comeback victory and inflicted a crushing defeat on Derby County.
Theo Robinson put the Rams ahead when he knocked in Mark O'Brien's pass and Robinson steered in his second from Jamie Ward's cross.
But Paul Taylor pulled a goal back when he fired into the roof of the net from 15 yards before the interval.
Tommy Rowe's close-range effort made it 2-2 and McCann's strike won the points.
The Rams were seemingly coasting to victory at 2-0 thanks to Robinson's cool opener and his 15-yard finish from Ward's left-wing cross.
Robinson then had a fine chance to seal his hat-trick and put the visitors three ahead but he skied his effort over the crossbar.
And Posh made Derby pay for their profligacy.
Taylor reduced the deficit when he collected Mark Little's pass and fired the ball home and George Boyd's willingness to chase saw him tee up Rowe, who slotted home the leveller from close range.
Both sides created chances after that, with home keeper Paul Jones tipping a Ward shot around the post just after the hour.
But it was Peterborough who grabbed the winner in a thrilling game when McCann blasted home a left-footed volley from the edge of the area in the third of five added minutes.
Posh are now ninth in the Championship table, just two points and two places behind the Rams.