Town are 1-0 behind and down to 10 men at half-time at home to Brentford, Sam Saunders having scored the Bees' goal and Luke Hyam having seen red just before the break, while visitors' winger Alan Judge was stretchered off early on with a broken leg.
Boss Mick McCarthy made four changes with Tommy Smith, Jonathan Douglas, Liam Feeney and Brett Pitman dropping to the bench and with Kevin Foley, Luke Hyam, Ainsley Maitland-Niles and Luke Varney all starting.
The Blues started in a 4-4-2 system with Foley at right-back and skipper Chambers at the centre of the defence alongside Christophe Berra.
Ben Pringle and Maitland-Niles were out wide in midfield with Cole Skuse and Hyam in the centre and Varney and Freddie Sears up front.
David McGoldrick was again on the bench but there was no place in the 18 for Teddy Bishop, who made his return as a sub against Charlton on Tuesday.
The game started in steady rain and was quickly brought to a halt when Hyam made a strong challenge on Judge, who was close to joining Town in the summer of 2013, leaving the former Blackburn man clearly in a lot of pain and requiring very lengthy treatment on the pitch for a broken leg.
The Blues midfielder looked to have made a genuine challenge and to have won the ball, but his momentum had taken him through the winger.
Hyam was booked with the Brentford players calling for a red, while Judge - who looked to be in the running for a place in the Irish squad for the Euros - was eventually stretchered off to applause from all sections of the ground. Konstantin Kerschbaumer took over in the Bees’ midfield.
Following a freekick after Varney had been somewhat cynically caught by Ryan Woods as he broke forward midway inside the Brentford half - far from the only niggly challenge from the visitors - Sears was played in down the right by Foley but Harlee Dean turned the ball behind for a corner.
On the quarter hour, with the game still to settle after the long stoppage, Brentford broke through three on one after Town had surrendered possession on halfway. Lasse Vibe found Kerschbaumer but his shot deflected off Berra and into Bartosz Bialkowski’s arms.
The visitors began to get on top but were unable to create an opening until the 29th minute when they scored a controversial opener.
Cole Skuse turned away from Kerschbaumer midway inside the Town half and looked to be tripped by the Austrian. However, referee Phil Gibbs waved away the Blues’ protests and Kerschbaumer brought the ball forward into the right of the area before cutting it back to Saunders, who smashed the it past Bialkowski from 15 yards.
While the Bees may have had the benefit of a poor refereeing decision, they had got themselves on top and had been looking the more likely scorers.
The Blues continued to struggle to make an impact on the game and in the 39th minute the visitors weren’t too far away from a second on the counter-attack, but Sergei Canos, having run from his own half, scuffed his shot wide. Referee Gibbs inexplicably awarded a corner, adding to the frustration of the home support.
On 42 Town created their first significant chance, Sears threading in Maitland-Niles on the left of the area, but the on-loan Arsenal youngster’s shot was too close to Bees’ keeper Button, who saved.
Judge’s treatment led to nine minutes of injury time in which the afternoon got worse for the Blues.
Woods caught Hyam on halfway and the Blues midfielder reacted by shoving the former Shrewsbury man, who pushed him back. Referee Gibbs booked both players and, having yellow-carded Hyam for the challenge on Judge, had no alternative but the show the Town midfielder his red card.
The Brentford players, clearly angered by the challenge which had led to the red card, had continued to bait Hyam throughout the half and it was probably only a matter of time before the midfielder reacted.
Having been reduced to 10 men, Town had their best spell of the game with Knudsen making a couple of strong runs down the left.
Following a corner, the Dane saw a shot blocked, Maitland-Niles crossed back into the box and the ball fell to Pringle, who also saw an effort stopped.
Soon after the referee’s whistle ended a half to forget for the Blues. Brentford had settled better after the early stoppage and were on top when they scored, even if the goal owed much to poor refereeing.
Hyam’s red card was foreseeable and the Town management may well have been planning to take him off at half-time. As it was, the Blues switched Maitland-Niles and Pringle for Jonathan Douglas and David McGoldrick ahead of the second half.