For the second time since Bruce's arrival as boss at the start of December, an error from the 26-year-old cost the Latics a goal, and more crucially points as Wigan suffered a 2-1 home defeat to Everton.
An horrendous attempted back pass late in the first half was pounced upon by Andy Johnson, allowing the striker to score his sixth goal of the season. Still reeling, Wigan conceded a second within three minutes as the Latics failed to clear a corner, culminating in Joleon Lescott popping up at the far post to poach his seventh of the campaign. After primarily dominating the half, Bruce was confronted with a 2-0 deficit at the break from which relegation-threatened Wigan failed to recover.
Phil Jagielka scored a 53rd-minute own goal to give Wigan hope, and while the home side had the majority of the possession in the second period, the equaliser never came.
"Unfortunately for Titus, he made a horrible mistake that has cost us badly," assessed Bruce. "I have to say he has been terrific since I came through the door, even though he got my career here off to a terrible start in the game with Manchester City after just 20 seconds.
"The boy has all the attributes to be a top player, but the one thing he has to do is work on his concentration levels. When you are playing at the back you get judged, and the great ones and good ones don't often make mistakes.
"Unfortunately for Titus, he makes a mistake and he gets punished badly, so we'll keep working on him. There's nobody more disappointed than him, but if we can increase the concentration levels, then we'll iron out the mistakes.
"Usually you get better with age and experience and improve as a defender, and let's hope he does."
After a miserable barren run to start the season, Johnson's six goals have come in his last 14 appearances.
This latest came from what boss David Moyes feels is Johnson's best position - playing as a lone striker.
"I thought he worried them," was Moyes' assessment of Johnson. "The mistake was because of the worrying he caused them. He was always on the edge of getting something, and in the end it proved that way.
"But I do think in a lot of ways it suits Andy playing on his own up front because he has bigger areas to run into. Sometimes playing against two defenders rather than one might suit him better because it makes him a bit more elusive and harder to be picked up."
With Ayegbeni Yakubu, Victor Anichebe and Steven Pienaar away on Africa n Nations Cup duty, for Moyes, his side ground out another win to keep them in the hunt for Champions League football.
"After going out of the FA Cup, we've bounced back brilliantly and our league form has been outstanding," said Moyes.
"The big thing for me is that before the game the players expected to win.
"That's coming through because they've a great deal of faith and belief, even if we're not quite hitting the heights."