Charlton took a huge step towards Championship safety with substitute Charlie Kelman's fifth goal of the season earning a 1-0 victory over Birmingham.
The former QPR frontman's clinically executed finish moved the Addicks nine points clear of the bottom three.
It was another hammer blow for the visitors' fading play-off aspirations as Chris Davies, marking his 100th game in charge of the Blues, lost three successive league matches for the first time since he took charge in June 2024.
It was Charlton that created the better of the frugal openings in the first half. Forward Lyndon Dykes, facing his former club for the first time since leaving at the end of the winter transfer window, produced an attempt to lob Ryan Allsop in the 19th minute but it failed to trouble the Blues keeper.
Harry Clarke was next to threaten for the hosts shortly afterwards, arriving on to Tyreece Campbell's dangerous fizzed low cross, but his attempt was blocked for a corner.
Birmingham midfielder Paik Seung-ho got his body in the way of Sonny Carey's shot from the edge of the box, play sweeping to the other end where Demarai Gray's shot deflected wide of the goal.
Charlton have not scored at home in the first half in their last 11 matches, a run stretching back to November 22.
Campbell was presented with an opportunity soon after the restart. Carey's header sent the Jamaica international racing through but he delayed in pulling the trigger and that allowed Christoph Klarer to make a crucial intervention.
The Blues livened up after a double change before the hour mark with Jay Stansfield and Ibrahim Osman coming on.
Birmingham began to gain more of an attacking foothold with Tomoki Iwata driving across the face of Will Mannion's goal from 20 yards out.
However, Kelman had only been on the pitch for two minutes before he struck from Carey's long throw to put Charlton ahead after 74 minutes.
Ibrahim Osman then whipped a right-footer just past the right upright for Birmingham, with home fans in uproar that referee Sam Allison had not awarded a free-kick moments earlier when Clarke went down on the edge of the Blues penalty area.
Kelman was presented with another shooting opportunity in the 87th minute but the angle was tight and he fired beyond the far post.
Charlton substitute Miles Leaburn also failed to finish a stoppage time chance but that did not prove to be costly as the hosts ended a four-match winless spell.
Charlton's Nathan Jones:
"It was a huge win. The level of performance was outstanding. We had a load of good chances. In the first half we were on top but couldn't find that little bit of quality.
"Every win is massive in this league and this stage of the season. I felt it was thoroughly deserved.
"Others had won or picked up points, so we knew we had to do that as well. It's all about us getting to a points total we're comfortable with and building from there.
"I don't think we're close [to safety]. You won't feel that way until it is mathematical. That wasn't our goal after the first 15 games. We didn't expect to be in this position.
"We picked up injuries at the wrong time but now we're coming through that. The performance levels have been good lately, we haven't lost many. Could we have won a few more? Yeah. Have we let ourselves down with one or two performances? Yeah. But we are fighting and competing at this level, it's only our first year back."
Birmingham's Chris Davies:
"The play-offs are very unlikely now. We probably needed to get something here today. We would need an incredible run, which has been done before, but we can put that to one side for now.
"It's about the next game and getting a result in that. We've got 10 games left, six at home and four away, we need to start getting some wins. We've still got a huge amount to play for.
"It was such a soft goal for us to concede. If you don't get the first contact and it bounces then you have reduced your chances significantly of keeping the ball out of the net. We didn't do either of those things. It's extremely frustrating to lose a game like that."
