A disastrous first-half away performance saw Reading FC beaten at St Andrews by Birmingham City.
In freezing conditions, the Royals were caught cold when Troy Deeney gave the Blues the lead after just 63 seconds.
Deeney had his double when he converted from the penalty spot and Tahith Chong pounced on another defensive mistake to make it three before half-time.
Lucas Joao and Tom Ince netted late in the game, but it wasn’t enough to complete a turnaround.
Paul Ince made two changes from Reading’s 1-0 win over Coventry last weekend as Shane Long and Naby Sarr came into the starting line-up.
Sarr, who made a sub appearance last weekend, hadn’t started since picking up an injury in August.
There was also a place on the bench for Femi Azeez after a spell out with injury who joined Lucas Joao and Andy Carroll in a set of diverse attacking options.
St Andrews greeted England star Jude Bellingham before kick-off, while his younger brother Jobe Bellingham was named on the Blues’ bench.
Birmingham were without top scorer Scott Hogan due to injury, who has nine Championship goals to his name this campaign.
With little over a minute on the clock Birmingham condemned Reading to a nightmare start and took advantage of a defensive lapse to take the lead.
Mamadou Loum flicked out his leg to deflect Bacuna’s cross which fell into the path of Troy Deeney who was given time and space to steer the ball past Joe Lumley.
Despite a hint of offside, with the replays showing that Deeney was marginally in front of the defender, the goal stood.
Having made a painfully frustrating start to proceedings, Reading tried to make amends through skipper Andy Yiadom when he struck a bouncing ball on the half volley and forced experienced goalkeeper John Ruddy into a fine save as he tipped onto the post.
Yakou Meite had a clear sight of goal when Tom McIntyre’s header looped into the box and was met by the Ivorian on the volley who connected sweetly but the ball went straight down the throat of Ruddy.
Having enjoyed a comfortable spell of possession, the Blues sprung into the box and were awarded a penalty after a neat one, two from Deeney and Tahith Chong ended with Deeney being scythed down by Sarr’s mistimed sliding tackle.
The Blues captain stepped up to the spot and slammed the ball past Lumley who guessed the opposite side.
Ruddy was forced into action again in the 35th minute, this time to deny Tom Ince who thumped a half volley at goal that was parried away.
Just a minute later, the Royals found themselves three goals down when Chong punished a defensive error.
After Amadou Mbengue swiped at the air from what looked like a harmless free-kick from Hannibal Mejbri, Chong raced through on goal, rounded Lumley and finished into the empty net.
With a miracle needed in the second-half, Reading came out with intent and won two early corners, but they were dealt with by the hosts.
The scoreline almost got even worse when a long ball for Chong wasn’t dealt with by the Royals defence and McIntyre had to block Deeney’s shot off the line to deny him his hat-trick.
Ince made a double change just before the hour mark which saw Lucas Joao and Junior Hoilett replace Mbengue and Long.
Deeney had another chance to clinch his treble but skewed his shot a whisker wide of the post.
Reading won plenty of corners throughout the half as Birmingham sat in a deep defensive line showing their willingness to sit on their healthy lead.
With 10 minutes to go, Ince made two more switches as Andy Carroll and Nesta Guiness-Walker came on for Meite and Rahman.
Reading salvaged back a goal in the 82nd minute when a deep cross found Carroll who fired across goal and after a scramble, Lucas Joao was on hand to convert from two yards out to reduce the deficit.
The Royals gave Birmingham a couple of minutes of anxiety in stoppage time when Ince’s deflected effort found the net in the 95th minute to make it 3-2.
The Royals threw everything they could in attack but it wasn’t enough as the Blues took three points.
Reading are back in action on December 27 at home to Swansea City.
Birmingham City: Ruddy, Colin, Sanderson, Trusty, Roberts, Longelo, Bielik, Hannibal, Bacuna, Chong, Deeney ©
Subs: Etheridge, Graham, James, Bellingham, Chang, Leko, Jutkiewicz
Reading: Lumley, McIntyre, Sarr, Yiadom (c), Rahman, Mbengue, Loum, Hendrick, Ince, Meite, Long
Subs: Bouzanis, Guinness-Walker, Azeez, Hoilett, Fornah, Joao, Carroll
Goals: Deeney 2’, 23’ (pen), Chong 36’, Lucas Joao 82’, Ince 90+5′
