Once all the acts have performed an 80s classic on Saturday night (12 October), the phone lines will open to the public for just 10 minutes.
Viewers will be asked to vote for who they want to save before the two acts with the least number of supporters are told there and then that they face a sing-off.
The sing-off will then take place during the live show on Sunday and the judges - Gary Barlow, Nicole Scherzinger, Louis Walsh and Sharon Osbourne - will ultimately decide their fate.
We can't imagine the two least popular hopefuls will sleep well on Saturday night after being told they are in the bottom two!
In a statement, an X Factor official said: "The dramatic new FLASH VOTE will take place at the end of the show.
"Once every contestant has performed, voting lines will open for under ten minutes, giving viewers the opportunity to save their favourite act from the bottom two.
"After voting lines have closed and the votes have been counted and verified, the contestant with the lowest number of votes will be revealed and told that they face the sing-off tomorrow night."
Do you like the sound of the Flash Vote? Tell us below, as the best comment from across the website each week wins £50!
Check out some pictures from this weekend's judges' houses below: