Lucas João missed from the penalty spot as the Royals fell to a costly defeat against bottom of the table Wycombe Wanderers who took the points through Fred Onyedinma’s decisive goal.
The Chairboys went ahead through Onyedinma early in the second half after Rafael fumbled the ball to concede a soft goal.
The game took a turn in the 69th minute when the Royals had the chance to go level when Ryan Tafazolli was sent off and gave away a penalty, but Lucas João hit the crossbar to miss his third spot-kick of the campaign.
Wycombe had a chance to wrap up the game with a penalty of their own but Rafael saved Uche Ikpeazu’s effort, but the hosts held on with 10 men to take the points.
The Royals came into the game against the Championship’s bottom side having lost three of their last four matches, with all of the defeats coming at home.
Wycombe manager Gareth Ainsworth named two former Royals in starting line-up, both of which had extensive spells at Reading. Jordan Obita graduated from Reading’s academy and made 191 appearances in 10 years for the club, while Garath McCleary played 270 times in eight years at the Madejski.
Club captain Liam Moore returned to Paunović‘s starting eleven after a spell on the sidelines with injury, while Tom Holmes also returned to start.
Wycombe started strongly and attacked in the Reading half for much of the opening 10 minutes of the match to give the Royals an uncomfortable start at Adams Park.
Tom McIntyre stayed alert to head clear after the Chairboys won a free-kick on the opening minute of the match, before Fred Onyedinma tried his luck from distance with a powerful strike that flew harmlessly wide of Rafael Cabral’s goal.
Former Royal McCleary caused problems on the right hand side when he broke into the box and clipped an inviting ball to the back post which Uche Ikpeazu leapt for but couldn’t reach to put the finishes touch on the move.
After a tricky start, Reading began to gain control in the match and create some chances of their own.
Ovie Ejaria picked out the run of Andy Rinomhota and perfectly weighted his pass to find his teammate, who looked to clip the ball over David Stockdale but the Wycombe keeper made a vital save.
Stockdale was called into action again in the 21st minute as Alfa Semedo took aim at goal from distance, but the keeper managed to clutch the ball safely.
A scramble in the box ensued after a Reading free-kick as Tom Holmes had a shot blocked before the ball dropped to Ejaria outside the box, but he could only skew an effort well wide of goal.
The two former Reading players in Wycombe colours combined with a clever free-kick routine as McCleary flicked the ball to Jordan Obita who tested the gloves of Rafael with a low strike, but the Brazilian got down to make a routine stop.
Ejaria was proving to be the bright spark in attack and linked well with Michael Olise and played a quick one-two, before he stung the gloves of Stockdale who had to fly to his left to prevent Ejaria’s strike from flashing into the top corner.
Wycombe could count themselves lucky to still have 11 players on the pitch when Josh Knight flew recklessly into a tackle on Morrison and caught the Reading defender on the shin. But the referee made his mind up quickly and produced a yellow card.
The half ended square after McIntyre’s header rose high over the bar in the last action of the first 45 minutes.
Reading made an equally poor start to the second-half as they did in the first and found themselves behind just four minutes after the break.
It was a soft goal to concede as Reading failed to clear the danger and Rafael fumbled the ball at the feet of Onyedinma who poked the ball in from close range.
On the hour mark, Reading were awarded a free-kick from shooting range, which was lined up by Olise, but his effort was blocked by the Wycombe wall as they preserved their lead.
Semedo tried to play Lucas João in behind the Wycombe defence but a strong piece of defending from Anthony Stewart saw the Portuguese forward uncharacteristically shrugged off the ball.
Josh Laurent came inches away from equalising in the 66th minute when his shot whiskered past the far post.
The game took a dramatic twist in the 69th minute when Rinomhota looked to be through on goal after a superb through ball threaded through from Ejaria, and the Royals were awarded a penalty when he was shoved to the ground by Ryan Tafazolli who received a red card.
But with a golden chance to level the game, João stepped up to the spot and crashed his penalty off the top of the crossbar.
George Puscas entered the play to replace Olise with just over 10 minutes of the match to try and salvage a result.
A few minutes later, Sone Aluko and Sam Baldock were introduced in place of Holmes and Ejaria.
Wycombe then had a chance to seal the game when they awarded a penalty of their own after McIntyre brought down Ikpeazu.
But a second spot-kick of the game was missed as Rafael got down low to his left to keep out Ikpeazu’s penalty.
Ainsworth’s side held on valiantly to gain just their fifth win of the Championship season as Reading’s miserable form continued.
Reading stay in fifth for the time being, but Bournemouth have the chance to overtake them when they play Cardiff City tomorrow night.
The Royals are away at Rotherham United on Saturday (3pm).
Wycombe Wanderers: Stockdale, Grimmer, Stewart, Tafazolli, Obita, Wheeler, Knight, Mehmeti, McCleary, Ikpeazu, Onyedinma
Subs: Gape, Kashket, Muskwe, Horgan, Thompson, Samuel, McCarthy, Ofoborh, Anderson
Reading: Rafael, Holmes, Moore (c), Morrison, McIntyre, Rinomhota, Laurent, Olise, Semedo, Ejaria, Joao
Subs: Esteves, Richards, Baldock, Yiadom, Aluko, Tetek, Puscas, Dorsett
Goals: Onyedinma 49′