With some of the best singing talents in one series, as the final of The X Factor draws nearer, the weekly elimination gets more and more brutal. This week saw Filipino sister act 4th Impact face Lauren Murphy in one of the toughest fought sing-off of the series with they sang for their lives, as they found themselves in the bottom two.

It was a controversial result, with both acts consistently showcasing their obvious singing talents. After Saturday's show, which saw Che Chesterman forget the lyrics to Adele's Hello and Reggie N Bollie, clearly not the strongest singers, there were suggestions that the wrong two acts were in the sing-off.

It was certainly a sentiment shared by their respective mentors Rita Ora and Cheryl Fernandez-Versini. Taking to the stage to sing Jennifer Hudson's And I'm Telling You, 4th Impact hit all the right notes as their voices spiraled into the air. And in a stripped back performance that showed off her powerful vocal control, Lauren tore the roof off with her version of Mariah Carey's Vision of Love.

Their mentors naturally backed their own acts. Rita Ora hailed Lauren as a future recording star saying: "I'm going for the person who's an artist, who can sell records, who I can envision with a career [and] I think standing alone is more powerful ... there's a future for Lauren."

"My heart and my soul was 100% with my girls. They sang every single note beautifully, in harmony. I'm with my girls," said Cheryl.

Nick Grimshaw threw a curve ball voting to save 4th Impact, but not before acknowledging the high standards of all the singers. "I can't remember a sing-off as emotional as that," he said. "It feels like there should be five finalists because everyone has sung so well on this stage."

After Nick saved the sisters, the deciding vote was left to Simon. "It's the best sing-off we've ever had," he said. "Honestly I couldn't call it either way. I think I'm going to send Lauren home."

Simon's decision took the competition to deadlock with 4th Impact receiving the fewest votes leaving Lauren to continue for another week.

"We just want to think British public for letting us sing on this stage. Even though we're Filipinos, you've accepted us an welcomed us," said 4th Impact as they tearfully exited the show.

The shock of the final result had clearly hit them hard after it was later revealed that one of the sisters Celina, collapsed after leaving the stage. An audience member told The Mirror: "Everyone was saying their goodbyes to the girls and then suddenly Celina hit the floor. Her sisters were shocked and Cheryl started calling for people to help.

Two men ran on stage and carried Celina backstage, she looked lifeless. Cheryl had to stay on stage because of Xtra Factor but she was clearly shaken by what had happened."

4th Impact took to Twitter on Sunday night to tell their fans that Celina is 'OK now' and to 'keep believing'. They wrote in a tweet: "Thanks to all who voted for us why we reach this far [sic]. Celina is ok now thanks for your prayers and love - love u guys. Lets keep believing [sic]."

The result garnered a mixed reaction on Twitter with viewers now questioning why Reggie N Bollie are being kept into the show over stronger singers. With just four acts left in the competition, next week's semi-final will really show us what the voting public are made of. Meanwhile, 4th Impact and Lauren raised the bar, showing everyone just how you do a sing-off.