A last-gasp Darren O'Dea strike sent Leeds leap-frogging Peterborough into the play-off places with a 3-2 win at London Road.
Peterborough levelled twice despite Lee Tomlin's first-half dismissal but were undone with the last kick of the game by a poacher's goal from the substitute striker.
The visitors were off to a flyer and went ahead in the fourth minute, Paul Connolly locating Andy Keogh and the forward firing high into the net from 18 yards.
Ross McCormack nearly doubled the lead soon after but it was all square in the 23rd minute when Grant McCann's cross was met with a solid header from Gabriel Zakuani.
A rash 40th-minute challenge from Tomlin on Keogh handed Leeds a man-advantage, and Adam Clayton piled on the misery nine minutes into the second period when he swept home from distance.
With just two minutes remaining, Ryan Bennett nodded down for Mark Little to ignite the crowd with a second equaliser that seemed certain to earn a point.
But it was not to be; Darren O'Dea swivelling to fire a vicious volley against the underside of the bar and Becchio bundling the ball to the back of the net to negate any doubt that the ball had crossed the line.