BIRMINGHAM inflicted Millwall's heaviest league defeat of the season by trouncing the Lions 6-0 at The Den this afternoon.

Kenny Jackett's side finished the game with nine-men after Shane Lowry and Alan Dunne were handed red cards either side of half-time, both for challenges on Nikola Zigic.

But the result was overshadowed by objects being thrown onto the pitch by Millwall fans after Birmingham's second went in, an incident which could have serious implications for the Lions.

The big pre-match news was that David Forde made his first start since picking up an injury in the 2-1 home defeat against Bristol City on November 20.

Dany N'Guessan really should have headed the Lions in front on there minutes when he met with Hameur Bouazza's delivery from the right, but inexplicably he placed his effort wide of the target from six yards when it looked easier to score.

Jack Smith was fouled by Jordan Mutch just outside of the area moments later, but Harry Kane's free-kick was deflected behind for a corner, from which the Spurs loanee headed over.

Only a scrambled clearance off the line from Jean Beausejour denied Kane a certain goal in the 12th minute.

And it was Kane who came close again on the quarter hour when he headed just over from Liam Feeney's cross, but despite dominating the early exchanges it was Birmingham who took the lead on 18 minutes with their first attack.

Mutch swung a free-kick into the area and it was very poorly defended by the Lions, allowing Davies to nip in and head past Forde.

Millwall's afternoon quickly went from bad to worse when they were reduced to 10-men four minutes later.

Nikola Zigic went in for a challenge on Lowry, but the linesman quickly raised his flag to signal the Lions defender had reacted badly to the tackle, presumably by leaving his foot in, and the referee produced a straight red card.

The home crowd were furious with the decision and Zigic was a marked man for the remainder of the game as far as they were concerned.

Feeney shot over in the 26th minute, while Mutch saw a 20 yard drive comfortably dealt with by Forde at the other end.

Kane twisted and turned in the box four minutes before the interval before his eventual shot was well blocked by Liam Ridgewell, while Blues keeper Boaz Myhill had to tip over another Kane three minutes later.

Marlon King saw an overhead kick go just wide in stoppage time but it was Birmingham who went in at the break with their noses in front.

King's dipping 49th shot from 25 yards was only kept out by a super stop from Forde, who did very well to tip it over, and the Lions keeper was called into action again seconds later to scramble away Davies' header.

King's 51st minute free-kick went just wide but Millwall were left really up against it six minutes later when another defender saw red when Alan Dunne left raising his foot in a challenge on Zigic.

The inevitable second goal on 59 minutes and it was that man King who grabbed it with a fine finish from inside of the area.

King's goal sparked more fury from the home fans and the kick-off was delayed for several minutes after the linesman on the far side was pelted with objects from the stand.

A line of stewards surrounded the touchline to protect him and they were joined shortly afterwards by police reinforcements.

What the implications of the incident will be for Millwall FC will only become clear later, but it will almost certainly feature in the referee's post-match report and FA censure is almost inevitable.

When play did resume Feeney saw a volley well saved, while King dragged a shot just wide at the other end with the official bizarrely deciding a Millwall player had got the last touch for a corner.

Birmingham's third arrived in the 74th minute when King found Chris Burke, whose curling shot flew past Forde.

Feeney had a goal disallowed for offside before Adam Rooney made it four with a shot from 20 yards.

King piled on the misery by rounding Forde and firing into an empty net in the 83rd minute.

And the horror show was completed in stoppage time when Nathan Redmond completed the rout.

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Millwall: Forde, Dunne, Robinson, Lowry, Smith, Feeney (Henry 85), Abdou, Trotter, Bouazza, Kane (Marquis 85), N'Guessan (McQuoid 71). Subs not used: Mildenhall, Craig.