Town eased their way into the fourth round of the FA Cup with a comfortable 3-0 home win over Chesterfield. All the goals came in the second half, Jon Walters netting a penalty before Pablo Couñago and Jon Stead joined him on the scoresheet.
The Blues made two changes from the side which defeated Derby at Pride Park last Sunday, Pablo Couñago coming in for Kevin Lisbie, who has a throat infection, and David Wright returning to the team in place of Moritz Volz after his hamstring problem.
As predicted on Friday, Town included young strikers Jordan Rhodes and Connor Wickham, who has been given the number 40 shirt, amongst the seven subs.
The game started slowly and neither keeper was involved until the ninth minute when Richard Wright pushed away Chesterfield striker Jamie Ward's shot, although the ball already appeared to be going wide.
On 17 Couñago sent Walters away down the left. The former Chester man crossed and the ball eventually found David Norris, but his shot flew wide of Chesterfield keeper Tommy Lee's goal.
Walters headed a David Wright cross to the keeper in the 24th minute but Town were rarely creating anything of note, despite enjoying most of the possession. On 29 Tommy Miller was replaced by Danny Haynes, the midfielder having taken a knock early in the match.
Just after the half hour, Alan Quinn played in Walters inside the area, but keeper Lee was out quickly to block. Quinn's subsequent strike flew high and wide.
Haynes forced Lee into a save with a powerful 20-yard strike from the right on 36 with Walters unable to seize on the rebound. A minute later, Veliche Shumulikoski got his name in the referee's book for a foul. The yellow card is the Macedonian's fifth of the season and he'll miss next week's home game against Sheffield Wednesday.
Couñago hit a shot on the turn wide in the 39th minute, prior to Ward cutting inside Thatcher but Campo blocking his shot.
With three minutes of the half remaining, Haynes crossed from the right, the ball reaching Quinn at the far post, but the Irishman failed to get any power in his strike. As the game moved into injury time, Lloyd Kerry was yellow carded for blocking a Haynes cross with his hand.
Town had been fairly disappointing, despite having the better of the half. Possession was given away too easily and there was a lack of quality in and around the box. At the other end, Chesterfield â€" who brought a much larger following than Birmingham on Boxing Day - had rarely shown that they were capable of creating a cup shock.
The opening goal took only three minutes of the second half to arrive. Quinn crossed from the left and Phil Picken somewhat blatantly and pointlessly raised his arm to block. The referee pointed to the spot and Jon Walters lashed the ball into the roof of the net for his sixth goal of the season.
Chesterfield came close to an equaliser almost immediately but Wright did well to block from Lloyd Kerry after the ball had reached the midfielder from a cross from the right.
The Town keeper swiftly threw the ball out to Shumulikoski, who moved it on to Walters, who sent Haynes away down the flank. The former England U19 man crossed deep to Quinn, who slipped the ball to Couñago, who deftly stroked the ball past Lee from six yards to all but seal the result.
Former Blue Darren Currie was introduced by the visitors to a mixture of applause and boos from his old fans in the 56th minute, three minutes before Jon Stead replaced Alan Quinn, Walters moving to wide left to allow the former Sheffield United man to play alongside Couñago.
Haynes shot over from 25 yards, the Stead saw an effort on the turn saved by Lee, the loose ball running safely for the Chesterfield keeper.
Alex Bruce returned from his four-match ban on 68 to take over from David Wright, who appeared to have taken a knock, at right-back.
Campo's 30-yard freekick deflected through to Lee in the 71st minute, then Kerry headed weakly to Wright from a Ward cross at one end and Norris hit an effort through to the Chesterfield keeper at the other.
With two minutes remaining, Jon Stead added the third, slamming home a Walters knockdown, his seventh goal of the season, all at home.
Town were never really in any danger after Pablo Couñago's second goal, the penalty having come at an ideal time. A Chesterfield goal at the start of the second half might have made it a nervy affair, but the Blues did enough to warrant their place in the fourth round without ever totally dominating the League Two side or playing particularly fluent football.
The draw for the fourth round will be carried out on Sunday afternoon at around 3.25pm after the Gillingham-Aston Villa game on ITV1 with MK Dons boss Roberto Di Matteo and former Wimbledon goalkeeper Dave Beasant selecting the balls. Town will be number 12.
Town: R Wright, D Wright (Bruce 68), Thatcher, McAuley, Campo, Shumulikoski, Miller (Haynes 29), Quinn (Stead 59), Norris, Walters, Couñago. Unused: Supple, Balkestein, Rhodes, Wickham. Att: 12,524.