According to the BBC, a spokesperson said: "Unfortunately Nigel has sustained an injury which means he is unable to perform and has had to withdraw from Strictly," with no dance off or elimination this week and everyone going through to the semi final.
With Harman and his partner Katya Jones out and viewers unable to see their Mary Poppins-inspired Charleston, only four couples remained in contention for the coveted 2023 glitterball trophy.
Layton Williams and Nikita Kuzmin finally achieved a perfect score of 40 points, an incredible comeback after last week's shocking public vote which saw them landing in the bottom two.
Ellie Leach and Vito Coppola turned in another high score with a quickstep to a Disney classic, while Bobby Brazier and Dianne Buswell, and Annabel Croft and Johannes Radebe did their best to impress judges Shirley Ballas, Craig Revel Horwood, Motsi Mabuse, and Anton Du Beke.
Here's all the action as it happened.
Next stop, the semi final
That's it for another week, and tonight's couples can leave the dancefloor safe in the knowledge that they'll all be back next week to take part in the semi final.
In next Saturday's show, the couples will have to perform two dances for the first time, so they've got a busy week ahead of them.
The scores carried over see Layton at the top of the leaderboard, followed by Ellie, then Bobby, and with Annabel in last place.
See you next week to find out who makes the Strictly 2023 grand final.
Bobby and Dianne manage that lift
Dirty Dancing fans won't have been disappointed by Bobby Brazier and Dianne Buswell's Salsa tonight, which was packed with iconic moments from the film.
Of course, the one everyone wanted to see was that overhead lift - which Bobby described as "the deal or no deal of the dance".
They just about managed it, although Dianne looked understandably nervous and didn't quite let go into the flying pose.
As Anton said: "It's quite a lot of pressure when you're doing a dance and everyone is waiting for the moment."
But Craig told them: "The lift unfortunately failed in my eyes," explaining that he wasn't holding Dianne steadily enough for her to let go of him.
He did add that it was Bobby's strongest performance to date.
Scores were 8, 8, 9 and 9 - 34 points.
Layton and Nikita finally get a 40
Layton Williams and Nikita Kuzmin have finally achieved that elusive perfect 40 points.
This was classic Layton and Nikita - full of drama, every move absolutely on point, and some incredible costumes.
Their Moulin Rouge! Paso Doble was one of their strongest routines and the perfect comeback from last week's debacle.
Layton and Nikita get their perfect 40
Motsi told them: "This is how you come back from a dance off. All of this negativity that you have been receiving...coming back week on week, never losing yourself...you were stunning."
Shirley added: "Absolutely first class team work," as she praised them for being perfectly in sync.
Anton called it "the best thing you've done on the series so far".
Obviously, the scores were all 10s - what an answer to being in last week's bottom two.
Nigel Harman explains why he has quit
Emotional scenes from the balcony as Nigel and Katya joined Claudia to explain why they have had to drop out.
Nigel said that he had broken a rib in training by jumping from a rostrum.
He said: "As I jumped from the rostrum, I was Peter Pan...as I landed, I was in A&E."
Nigel looked in quite a lot of pain as he clutched his rib and said: "I'm quite high on painkillers right now."
Katya was in tears at their early exit, as she said: "It's quite hard to talk right now, I'm not going to lie."
Nigel praised her for making every day fun, adding: "You're just part of me now, I can't even look at you."
Goodbye, Nigel and Katya!
Annabel and Johannes' Wicked Foxtrot
Annabel Croft looks every inch a West End star tonight in her Wicked costume, complete with green face paint.
She and Johannes Radebe have gone from strength to strength each week, and now they're guaranteed a semi final place.
The judges loved tonight's Foxtrot, with Anton telling Annabel she has "the best frame in the competition by far".
Annabel has 'the best frame in the contest'
Craig pointed out how well Annabel is doing as the only non-actor left in the cast, while Motsi Mabuse said the performance almost brought her to tears.
Head judge Shirley Ballas said: "Throughout the competition, you have really stood out amongst everybody."
Scores for Annabel and Johannes are 8, 8, 8 and 9, making 33 points - the highest for a Foxtrot this series.
Beauty and the Beast opens musicals week
Ellie Leach and Vito Coppola brought the Disney magic with a Beauty and the Beast Quickstep.
As usual, the Strictly wardrobe department have done a great job and competition favourite Ellie did them proud with a perfect dance as Belle.
Ellie and Vito look really comfortable on the dancefloor now and the comments reflected that - Anton Du Beke said: "What a tremendous opening number," while Craig Revel Horwood added: "I absolutely loved it."
Ellie and Vito are the competition favourites
Scores for Ellie and Vito are all nines, making a total of 36 points - but as Claudia explained, tonight's scores will be carried over to next week as there'll be no dance off.
No public vote or elimination this weekend
Hosts Claudia Winkleman and Tess Daly have confirmed that there will be no one going home this weekend - so hold the phones, there's no need to vote tonight.
Announcing Nigel Harman and Katya Jones' exit, Tess said: "We are as devastated as he is but Nigel and Katya will be here to chat to us later."
Claudia confirmed: "That means there will be no public vote tonight and no elimination this weekend."
Here's the quarter final line-up...
The quarter finals are here - but one couple isn't
It's the Strictly 2023 quarter final and musicals week has arrived, but chaos has hit the cast just hours before the live show was due to begin.
Nigel Harman has been forced to quit over an injury, so sadly viewers won't get to see the Mary Poppins-inspired Charleston that he and Katya Jones had been rehearsing.
As we bid a sad farewell to Nigel and Katya, we wait to see who will get an encore in movie week - and whether anyone will have to face the dance off now that the numbers have dwindled to four couples
When Strictly is broadcast on BBC One this weekend?
Strictly Come Dancing's live show will air at 7:25pm, Saturday, 2 December on BBC One.
Strictly Come Dancing's results show will air at 7:20pm, Sunday, 3 December on BBC One.
Strictly musicals week: Quarter-final routines
Annabel and Johannes: Foxtrot to For Good from Wicked
Bobby and Dianne: Salsa to (I’ve Had) The Time of My Life from Dirty Dancing
Ellie and Vito: Quickstep to Belle from Beauty And The Beast
Layton and Nikita: Paso Doble to Backstage Romance from Moulin Rouge! The Musical