Victoria delivered one of the stand-out moments on the ITV talent contest's most recent episode.
Her cover of INXS classic 'Never Tear Us Apart' won rave reviews from the judges, with Nicole Scherzinger calling it "effortless".
Meanwhile, Simon Cowell said it was "a great performance full stop" and suggested she proved he was right to make a celebrity version of the show.
However, the Coronation Street actress has hit a setback as she prepares for her next appearance.
A show insider told the Metro that Victoria has been skipping rehearsals, as her vocals aren't up to scratch.
She is not the only celeb feeling under the weather, as Martin Bashir is currently suffering from a cold.
"Martin has had a bit of a cold this week so he has been a bit congested, but the vocal coaches have been advising him on what to do," the mole revealed.
"Victoria’s voice is also strained so she is on voice rest today. People have been rallying round offering to help and make her cups of tea."
Barring a turn for the worse, they are both still due to take to the stage on Saturday.
The illness couldn't have come at a worse time for Martin, who narrowly escaped the latest elimination.
The journalist was up against Olivia Olson in the judges' vote, but a shock result saw Simon send her home in floods of tears.
Viewers heavily criticised his decision on social media, while Olivia herself described it as "a punch in the gut".
Twelve acts remain in the contest, with two more set to face the chop this weekend.
The X Factor: Celebrity continues on Saturday at 8.00pm on ITV.