The Baggies had been in cruise control after Belgian international striker Romelu Lukaku had put them 2-0 up and hit the woodwork twice. Reading seemed down and out. A return to the bottom of the table, after QPR's draw with Tottenham earlier in the day, seemed inevitable.
But Jimmy Kebe grabbed an opportunist goal to set up a tense finish and the Royals snatched victory from the jaws of defeat by completing a dramatic late turnaround.
Le Fondre came off the bench to draw Reading level with an 88th minute penalty after Kebe had been fouled by Jonas Olsson before Pogrebnyak bundled in the winner from an Ian Harte free-kick.
West Brom cut the home side open with ease to score the opener. Lukaku, on loan from Chelsea until the end of the season, released James Morrison down the left and then received the return ball to beat Adam Federici from six yards out.
Reading were booed off at half-time and fortunate not to go further behind immediately after the restart, when Harte sloppily conceded possession and Lukaku almost doubled his tally.
Chris Brunt preserved West Brom's lead with a last-gasp block to deny Garath McLeary after Ben Foster had missed Kebe's cross from the right.
Lukaku had one strike chalked off for offside before he hit the post with a glancing header after Morrison's excellent run and cross down the left. The forward then rattled the crossbar with a thundering left-foot strike off the bar before finally hitting the target again, drilling a low shot past Federici.
There seemed no way back for Reading but with 10 minutes left Kebe snuck in at the back post to beat Foster with a low header. Reading began to press hard and, with two minutes remaining, Kebe was clattered by Olsson on the edge of the West Brom box. Le Fondre, who blasted a penalty in the FA Cup win against Crawley, this time tucked it away calmly to Foster's left.
And an incredible comeback was completed when Harte launched a free-kick into the box, Alex Pearce knocked it down and Pogrebnyak bundled the ball past Foster.
Source: PA
Source: PA