READING FC squandered a two-goal lead as top of the table Portsmouth fought back to protect their long unbeaten record.
Strikes from Lewis Wing and Charlie Savage had the Royals in command, but Pompey responded with goals from Tino Anjorin and Colby Bishop to level before half-time.
Portsmouth completed the turnaround before the hour when Terry Devlin slammed home to ensure the visitors made it 26 matches unbeaten.
The defeat means Reading drop down to the bottom of the table after Cheltenham moved above them with a win.
On a day that saw thousands of Reading fans march from the town centre to the Select Car Leasing Stadium to protest against club owner Dai Yongge, there was also plenty of action from 3pm onwards on the pitch.
The Royals fans turned out in force with thousands taking part in the march, including Reading legend Dave Kitson who led the protest from Blue Collar Corner to the Mad Stad.
Pompey came into the match flying high at the top of the table, unbeaten for the entire campaign with a run stretching back to last season of 25 games without tasting defeat.
Meanwhile, Reading were looking for their first win in six League One matches having been beaten five times in that stint, leaving them in 23rd place and eight points adrift of safety.
Ruben Selles switched up his formation for the first time this season, reverting to a 4-3-3 instead of his favoured 4-2-2-2.
The opening 20 minutes of the game were broken up with breaks as the game was twice paused after Reading fans threw tennis balls onto the pitch, which has become a trend in recent home games to protest against club owner Dai Yongge.
Paddy Lane tried to ignite Portsmouth with a counter attack from Reading’s corner when he skipped past a steaming attempted tackle from Andy Yiadom and tried to catch out David Button who took a simple catch.
It was Reading who drew first blood in a relentless opening 45 minutes when Lewis Wing connected sweetly on the half volley to smack the ball past Will Norris with 23 minutes on the clock.
The Royals added to their advantage just four minutes later when Harvey Knibbs kept the ball alive from Yiadom’s cross and Charlie Savage arrived to arrow the ball into the far corner with a superb finish.
It was a dream five minute spell for Reading, but the jubilation in the home end was short lived as Portsmouth, looking to protect their long unbeaten run, hit back when Tino Anjorin met a cross and swept the ball into the bottom corner with a smart finish.
Sam Smith had a golden chance to restore Reading’s two goal lead when he raced past a defender, skipped past the onrushing goalkeeper, but with the goal gaping he lifted the ball over the top much to the relief of the visitors.
Reading were punished deep into added time as they saw their two goal lead disappear when Colby Bishop was left unmarked in the middle and put Pompey on level terms.
The first chance after the restart went Pompey’s way when Reading failed to deal with a corner and Anjorin tried a spectacular acrobatic effort that was brilliantly kept out by Button.
Pompey put Reading under constant pressure in search of going in front for the first time in the contest.
The pressure proved to be too much for Reading to cope with as Bishop cushioned a header into the path for Terry Davlin to lash the ball past Button.
Selles responded with a triple change that saw Amadou Mbengue, Ben Elliott and Paul Mukairu replace Guinness-Walker, Azeez and Knibbs.
Two more attacking changes saw Kelvin Ehibhatiomhan and Dom Ballard enter the contest in place of Savage and Smith for the final 15 minutes to try and claw back a result.
The subs combined to forge a brilliant opening when Elliott threaded a pinpoint ball into the path of Ehibhatiomhan who was denied by Norris.
Button made his way up for a 95th minute corner and the ball fell to him after a short set-piece routine, however the keeper failed to hit the target.
But the chances dried up and Reading were beaten for the 10th time in 15 league matches to put them bottom of the table.
Reading: Button, Yiadom, Dean, Bindon, Guinness-Walker, Savage, Craig, Wing, Knibbs, Azeez, Smith
Subs: Pereira, Elliott, Ballard, Mukairu, Ehibhatiomhan, Abbey
Portsmouth: Norris, Poole, Robertson, Bishop, Morrell, Rafferty, Shaughnessy, Sparkes, Devlin, Anjorin, Lane
Subs: Schofield, Swanson, Whyte, Saydee, Yengi, Raggett, Kamara
Goals: Wing 23’, Savage 27’, Anjorin 33’, Bishop 45+9’, Devlin 58’