Match ends, Sheffield Wednesday 1, Charlton Athletic 2.
Simon Church's winner against Sheffield Wednesday saw Charlton prevent an all-Sheffield FA Cup quarter-final tie.
Wednesday and United met in an FA Cup semi-final at Wembley in 1993 and a potential Steel City derby had been anticipated since the draw was made.
But Church's header just after the hour mark ensured it will be Charlton who will play the League One Blades.
Wednesday striker Leon Best had earlier equalised Callum Harriott's first-half opening goal for the Addicks.
The fixture had been originally scheduled for 15 February, but was postponed because of a waterlogged pitch at Hillsborough.
Since then, relegation-battling Charlton have beaten Championship promotion hopefuls QPR and their confidence continued into this fifth-round tie.
The visitors began positively and Swedish playmaker Astrit Ajdarevic served notice of Charlton's attacking intent with a shot which went just past the post after being set up by the lively Harriott.
Wednesday struggled to find their rhythm and were punished by Charlton, who took a deserved lead through Harriott in the 22nd minute after some neat build-up play.
Ajdarevic's initial shot was blocked and Harriott struck a sweet half-volley with his left foot into the roof of the net from just inside the penalty area.
The Addicks had another chance moments later when Wales striker Church seized on a loose ball, only to watch his deflected effort easily gathered by Damian Martinez in the Wednesday goal.
The hosts enjoyed a spell of pressure before half-time and midfielder Gary Gardner, on loan from Aston Villa, struck a first-time effort from 25 yards straight at Charlton goalkeeper Ben Hamer.
The hosts were given a let off of their own in first-half stoppage time when Church tried to break clear of the Wednesday defence and appeared to be held by Spanish defender Miguel Llera, but referee Mark Clattenburg ignored Charlton's appeals.
Charlton looked the more likely side to score immediately after the interval and Johnnie Jackson had Martinez, on loan from Arsenal, scrabbling to his left with a long-range attempt.
And it was another loanee in Best, who joined from Blackburn 10 days ago, that got the Owls on level terms just before the hour mark. Chris Maguire's free-kick was headed down by Llera and Best swept the ball home from close range.
Charlton regained the lead eight minutes later when Church took advantage of some sloppy Wednesday defending to head a Jackson free-kick past Martinez.
Wednesday substitute Atdhe Nuhiu saw a header hit the inside of the post, with Hamer reacting brilliantly to scramble the ball away from on the goal-line.
And Charlton boss Chris Powell was indebted to another late save from Hamer, who hurled himself at Maguire's deflected shot in injury time to turn the ball away from the top corner and deny Wednesday a replay.
Charlton boss Chris Powell:
"Our keeper Ben Hamer made some cracking saves but that's cup football.
"It's not been the greatest campaign for us in the league - that's an understatement - but this means a lot. That's two huge results in 72 hours. You savour these moments because there have been plenty of dark moments.
"We've got a real chance now of getting to the semi-finals, but it will be very tough against Sheffield United, who've had some really good results in the cup.
"It's going to be another tough game, if not harder because people will be looking at us the favourites, that's going to be tough game.
"Nigel (Clough) and his team will be thinking the same thing. They want to get to Wembley. A Football League side will be in the last four and we'll be trying our hardest to make it us."
Sheffield Wednesday head coach Stuart Gray:
"You can't play like we did in the first half and expect to win games of football.
"It was 27 minutes I think before we got a cross into the box, about 40 minutes before our first shot, 41 minutes before our first tackle and 44 minutes before our first corner.
"You're not going to win games of football playing like that. That's the worst 45 minutes of football I've been involved with at the club.
"The players have missed a great opportunity to look back over their careers and have on their CV a quarter-final of the FA Cup against your local rivals.
"I just couldn't see it coming. It was an FA Cup quarter-final at stake and it's a big disappointment."
- 19MattockBooked at 77mins
- 40GardnerSubstituted forNuhiuat 58'minutes
- 36LoovensBooked at 67mins
- 32LleraBooked at 64mins
- 42BestBooked at 62mins
- 28AfobeSubstituted forHelanat 74'minutes
- 10MaghomaSubstituted forLaveryat 58'minutes
- 15WoodBooked at 88minsSubstituted forDerviteat 90'minutes
- 9ChurchSubstituted forGhoochanneijhadat 85'minutes
- 42AjdarevicSubstituted forHughesat 90+3'minutes
- Mark Clattenburg
- Shots on Target
Second Half ends, Sheffield Wednesday 1, Charlton Athletic 2.
Attempt blocked. Chris Maguire (Sheffield Wednesday) right footed shot from the centre of the box is blocked. Assisted by Damián Martinez.
Foul by Glenn Loovens (Sheffield Wednesday).
Michael Morrison (Charlton Athletic) wins a free kick in the defensive half.
Corner, Sheffield Wednesday. Conceded by Ben Hamer.
Attempt saved. Chris Maguire (Sheffield Wednesday) right footed shot from outside the box is saved in the top left corner. Assisted by Miguel Ángel Llera.
Substitution, Charlton Athletic. Andy Hughes replaces Astrit Ajdarevic.
Offside, Charlton Athletic. Astrit Ajdarevic tries a through ball, but Reza Ghoochanneijhad is caught offside.
Attempt missed. Astrit Ajdarevic (Charlton Athletic) left footed shot from outside the box misses to the right from a direct free kick.
Foul by Glenn Loovens (Sheffield Wednesday).
Diego Poyet (Charlton Athletic) wins a free kick in the attacking half.
Substitution, Charlton Athletic. Dorian Dervite replaces Richard Wood.
Attempt missed. Atdhe Nuhiu (Sheffield Wednesday) header from very close range is too high. Assisted by Chris Maguire with a cross following a corner.
Corner, Sheffield Wednesday. Conceded by Callum Harriott.
Attempt blocked. Chris Maguire (Sheffield Wednesday) right footed shot from outside the box is blocked.
Richard Wood (Charlton Athletic) is shown the yellow card for a bad foul.
Atdhe Nuhiu (Sheffield Wednesday) wins a free kick in the attacking half.
Foul by Richard Wood (Charlton Athletic).
Attempt blocked. Giles Coke (Sheffield Wednesday) right footed shot from the centre of the box is blocked.