The three-piece vocal group will perform in the bottom two during Sunday's results show after receiving the fewest number of public votes.
They told host Dermot O'Leary they will "do nothing but rehearse" for the next 24 hours.
"We have an advantage over whoever is put in the bottom two tomorrow night," said band member Jeanette. "We are going to rehearse all night."
Miss Dynamix, who were put together by mentor Gary Barlow during Bootcamp, returned to the competition on Saturday after being forced to pull out of last week's show when pregnant member SeSe fell ill and had to be rushed to hospital.
The group were given a free pass to this week's movie themed show and said they were determined to prove they deserved to be in the competition.
However following their performance of Gabrielle's 'Dreams', judge Nicole Scherzinger told them she felt like their vocals and energy as a group "are not going to cut it".
But she added: "We do forget that you guys just came together recently and we do have to take that into account."
It was a good song but I do feel that there was some connection missing.
Sharon Osbourne to Miss Dynamix
Louis Walsh agreed, telling them: "I feel that you are not really working as a girl group, I think there is some chemistry missing.
"I expect more," he added.
Meanwhile an emotional Abi Alton was reduced to tears following her acoustic rendition of 'Moon River' from the film Breakfast at Tiffany's.
Sharon Osbourne praised the singer for giving such a stripped back performance, but she felt it lacked "charisma".
She said: "You sang it beautifully, however, the performance, what are we going to do with you Abi?
"People are going to put on the kettle when you start singing. You've got to keep people awake. You need emotion and charisma and I'm not feeling it from you."
Vocal group Rough Copy opened the show with a rendition of Bryan Adams' 'Everything I Do', while fellow group Kingsland Road gave a "slick" performance of the movie classic 'Pretty Woman".
Sharon told Sam Callahan he needed "more edge" following his rendition of U2's 'All I Want Is You' and Nicholas McDonald performed Sarah McLachlan's 'Angel'.
Just when you thought it couldn't get any better you come out and you do a Beyonce number - you stole the show.
Louis Walsh to Tamera Foster
Luke Friend not only washed his hair this week, but he also received high praise for his performance of Seal's 'Kiss from a Rose'.
Sharon told him: "You have got such a distinctive vocal sound. That was the perfect song choice for you."
Hannah Barrett giving a rousing performance of Adele's 'Skyfall' while Sam Bailey had the crowd on their feet following her performance of Celine Dion's 'My Heart Will Go On'.
Tamera Foster, 16, finished Saturday's show with a rendition of Beyonce's 'Listen'.
But while Louis felt she had "stole the show" with her performance, Gary told her he thought it had too much of a "Stars in Your Eyes" feel.
He said: "Tamera, that was another amazing vocal performance, but because you are so good I am going to say this to you, this show is called The X Factor, there were elements of that performance that reminded me of Stars in Your Eyes.
"You are not a Beyonce impersonator," he added.
Who will join Miss Dynamix in the sing off? Find out during the results show on Sunday on UTV from 8pm.