Town failed to take the chance to six points clear at the top of the table after losing 2-1 to Watford. The Blues were under par throughout and the visitors went ahead via Jay Demerit's header just before the break, Bruce Dyer adding to their lead prior to a late Tommy Miller penalty.
As expected, skipper Jim Magilton returned to the side but in place of Darren Currie and not Kevin Horlock. The two former Northern Irish internationals started in the centre of midfield with Ian Westlake wide on the left. James Scowcroft received a warm welcome on his second home debut, his 250th appearance for the Blues.
Despite the snowy weather in the last few days and during the game, the pitch looked unaffected, although it appeared harder than usual.
Watford's approach was clear from the off with the first 20 minutes of the game played almost uniformly in their half of the field. Town dominated the possession and eked out a few early chances.
Scowcroft headed Bent's right wing cross wide, before Miller struck a powerful volley straight at keeper Jones. The Welshman couldn't hold on to the ball but managed to block Scowcroft's follow-up.
Miller again came close to scoring in the 22nd minute. The midfielder shot wide when well placed inside the area after Scowcroft had laid off a De Vos knockdown from a long Wilnis throw on the right.
Just before the half hour mark Miller played a good ball to Bent, the striker taking the ball on and cutting in from the right but his shot failed to test Jones.
Soon after, Miller and Scowcroft played a neat one-two on the edge of the Watford box, the midfielder shooting straight at the keeper.
Watford were gradually getting more into the game and in the 31st minute Richard Naylor did well to block a Bouazza cross from the left at the near post.
Town's finishing again let them down in the 34th minute when Scowcroft found Westlake with a header. The midfielder played the ball to Bent but he again shot weakly to Jones.
Perhaps inevitably given Town's profligacy in front of goal, Watford went in front with their first shot of the game. The Blues failed to clear the ball after a corner and Jay Demerit headed a cross from the right past Kelvin Davis, perhaps off Richard Naylor.
The goal was very much against the run of play, but despite creating a number of chances the Blues were far from at their best. After the early dominance and pressure had failed to yield a goal, Town started to look nervy, failing to hold on to the ball and with a midfield short on ideas.
Darren Bent had a golden opportunity to put the Blues back on terms four minutes after the break. Scowcroft's flick sent the England U21 away one-on-one with Jones but the striker stabbed the ball inches wide of the post.
Two minutes later, Scowcroft picked up what is definitely his fifth booking of the season for what seemed to be an accidental handball. Referee André Marriner may have decided to caution the striker as a similar incident had taken place in the first half. Scowcroft will now miss the crucial top of the table clash at Wigan a week on Saturday.
Joe Royle decided to make a change in the 56th minute, Darren Currie taking over from Ian Westlake on the left of midfield.
Town were still not into their rhythm with Watford continuing to close down quickly whenever the Blues had the ball. The midfield's failings led to a tendency to play longer balls aimed at Scowcroft's head or for Bent to chase.
Despite this, the Blues could have been back on terms in the 63rd minute. Bent was sent away down the right with Currie in space on the far side of the penalty area. However, the off-form frontman took too many touches as he brought the ball into the box and lost possession.
Five minutes later, Bent did find Currie with a pass, the former Brighton man fizzing a shot from an angle on the left and Jones parrying. Tommy Miller was quickest to the loose ball but somehow scrambled it the wrong side of the post.
Currie and Bent combined again in the 71st minute, the midfielder looping the ball between defence and keeper and Bent shooting over the bar as the ball came to him from over his shoulder.
Watford chances were rare but Chris Eagles, a loanee from Manchester United, wasn't too far away with a volley wide from a Jermaine Darlington cross from the left.
Two minutes later, the Blues had another chance, Unsworth crossing from the left, Bent heading back across goal and Miller again putting the ball wide.
With 12 minutes left, Joe Royle switched Fabian Wilnis for Dean Bowditch, the Blues moving to three at the back. Bowditch was immediately into the action and screwed a shot wide from 20 yards after a freekick was cleared to him.
Watford went further ahead in the 80th minute when a completely unmarked Bruce Dyer headed Johnnie Jackson's left-wing corner past Kelvin Davis. Quite who was supposed to be keeping an eye on Dyer was anyone's guess.
Bowditch went looking for a goal back and a strong run ended with a 20-yard shot flying just wide of Jones's post.
The Blues threw men forward as they sought goals and as a result were almost caught on the break, Davis doing well to save the aptly named Dominic Blizzard's header from Bouazza's cross.
Bowditch crossed for Bent on 84, the more senior of the two young strikers forcing Jones to tip over his bar.
Bent came even closer a minute later when a mix-up between Jones and Cox allowed him to get on to the ball and lob it over the keeper. In a moment which seemed to sum up Town's entire evening in front of goal, the striker watched disbelievingly as the ball rebounded off the bar.
A goal finally did come, from the penalty spot. Neil Cox handled a deep Currie corner and picked up a yellow card for his trouble. Tommy Miller continued his 100% record from the spot, shooting low and hard to Jones's left and into the corner of the net.
The Blues went looking for an equaliser and, with the game in injury time (or perhaps more accurately time-wasting time), Darren Currie struck a powerful volley from the edge of the area which Jones pushed round his post.
Late on, with Town defenders still committed forward, Dyer had the chance to add a third, but with the unmarked Bouazza available to him in a better position, curled the ball wide of Davis's post.
A hugely disappointing night for Town. The Blues were a long way from their best and yet still created enough clear-cut chances to win the game several times over. Darren Bent in particular will wonder how he failed to score, while Tommy Miller also missed a number of good chances prior to converting the late penalty.
Bent looks short of confidence, as did many of the team, which seems strange for a side top of the league. The midfield failed to function at its best with Watford harrying and hassling from beginning to end.
Ray Lewington clearly came with a game plan to frustrate and stop Town playing and the Watford boss will feel his side carried out his instructions to the letter.
Sunderland's 4-1 win against Rotherham puts them just three points behind the Blues with the same goal difference. Wigan, with a superior goal difference, can go top if they win at Coventry on Wednesday.
Town: Davis, Wilnis (Bowditch 78), Unsworth, De Vos, Naylor, Magilton, Horlock, Westlake (Currie 56), Miller, Bent, Scowcroft. Unused: Price, Richards, Karbassiyoon. Att: 23,993.