Two late goals from promotion-chasing Sheffield United left Reading beaten at Madejski Stadium on Saturday evening.
Substitute and former Royal, Billy Sharp, struck from close range six minutes from time, before a Jack O'Connell header took a heavy deflection from Sam Baldock on its way in two minutes later.
It was a defeat that was perhaps harsh on the Royals, who had been more than a match for their high-flying opponents for most of the game.
Caretaker boss Scott Marshall named a side with one change from the previous weekend's match against Stoke, with Josh Sims replacing John Swift.
On a clear but chilly night at Madejski Stadium, the Royals started brightly. An Andy Yiadom cross was headed away and into the path of an unlikely source of strikes in Chris Gunter. He controlled and fired from 25 yards, but his shot cleared the bar comfortably.
It was a lively start from both sides in RG2 - but former Royal, Ollie Norwood, stood over a dangerous free-kick after being brought down by Andy Rinomhota on the edge of the box. No trouble for Anssi Jaakkola on this occasion, though, floating safely into the Eamonn Dolan Stand behind.
Reading breathed a sigh of relief soon after, with a corner headed towards goal by John Egan flicking on for Conor Washington to nod in - but the striker's intervention prompted the flag to go up for offside and the scores remained level.
A loose ball in midfield then saw Norwood able to pick a pass over the top of the Royals' defence, with David McGoldrick giving chase. He beat Tiago Ilori to it, tried to chip Jaakkola but his effort limply made its way to the big Finn between the posts. Reading were riding a wave of pressure from the visitors.
But Reading had a chance of their own after Danny Loader was brought down by Norwood. Bacuna swung a free-kick to the near post, that Enda Stevens had to be alert to clear.
The heavens opened and the Royals grew into proceedings midway through the first period, seeing plenty of the ball and looking to be the aggressors in a stalemate in RG2.
Up the other end, the Blades broke - somewhat against the run of play at that point - and had the ball in the net again after George Baldock's low cross was turned in by McGoldrick. However, the assistant's flag was raised once again.
Time ticked on towards the interval but the Royals kept going for an opener. A quick midfield passing move saw Bacuna play to Sims 20 yards out. The space opened up for him to have a go, but he couldn't direct his strike on target with Dean Henderson untroubled.
Neither side was able to break the deadlock before the interval.
Half-time | Reading 0-0 Sheffield United
The visitors started the second period on the front foot, with McGoldrick getting played in on goal - striking low but Jaakkola was able to parry around the post. The resulting corner came in and was headed goalward, but Gunter's crucial intervention on the line prevented the opener.
Chris Wilder's side pushed on with more of the pressure going forward, but the Royals stood firm to deny their openings at goal.
Baldock the younger cut inside for the Blades to play to Fleck in space outside the box. He took a pot-shot at goal and Jaakkola watched it over the bar to safety for Reading.
It wasn't long before Sam Baldock and Mo Barrow were introduced for the Royals, with Scott Marshall looking to break through a Blades defence that had been seldom tested up to the hour mark. Meanwhile, the ever-dangerous Billy Sharp - who already has 11 goals to his name this season - was introduced for the Blades.
Jaakkola's gloves were soon tested again with George Baldock crossing in for McGoldrick to head down, but the Finn was behind the ball and gathered comfortably.
Travelling Blades fans were up and celebrating when they thought they had taken the lead through a bullet diving header from substitute Sharp - but it only grazed the side netting on the wrong side of the post from the visitors' point of view.
The clock carried on towards the final 10 minutes of action at Madejski Stadium, with the promotion-chasing visitors looking the more likely to get the opener late on in the game.
A Fleck free-kick was powerfully punched away by Jaakkola, before young Loader threw himself in the way of the rebound in a bullish defensive display from the Royals.
Eventually, the Royals' resistance was broken. A cross from the right touchline from Basham was deflected through the area with Sharp there to pick up the pieces and poke the Blades in front from five yards. It was a cruel blow on Reading, who had defended resolutely up to that point.
With the Royals still looking to set themselves after going behind, the Blades quickly doubled their advantage.
A cross from Fleck from a corner was headed at goal by centre-back Jack O'Connell, it took a wicked deflection off Sam Baldock on its way in and is likely to be listed as an own goal against the Royals striker.
Full-time | Reading 0-2 Sheffield United
Reading: Jaakkola, Gunter, Yiadom, Ilori, Blackett, Bacuna (c), Rinomhota, Sims (Barrow 64), McCleary (Aluko 86), McNulty (S Baldock 64), Loader.
Unused subs: Mannone, Swift, Kelly, McIntyre.
Sheffield United: Henderson, G Baldock, Stevens, O'Connell, Basham, Fleck, Lundstram (Duffy HT), Egan, Norwood, McGoldrick, Washington (Sharp 60).
Unused subs: Moore, Coutts, Stearman, Johnson, Cranie.
Goal: Sharp 84, Baldock OG 86
Referee: Mr J Linington
Attendance: 12,066 (1,066 away)