The boxing champ has been left on rest ahead of Saturday's first live show after eating some dodgy chicken.
Now the 37-year-old - who is partnered with pro Sita Bhuller on the show - is worried he won't be up to scratch when the new BBC One gymnastic series kicks off at the weekend.
A source said: “Carl has been eating lots of chicken as he’s bulking up on protein to make sure he’s as strong as possible.
“But a dodgy batch has really knocked him off his feet and made him miss a lot of training."
Speaking to The Sun newspaper today, the insider continued: “Carl takes his training really seriously and was devastated that he couldn’t carry on.
“But a lot of the training has been four metres off the ground in a hoop — and that’s not easy when you’re queasy.
“The show starts in just a few days’ time so Carl is desperate to get fit and up to speed."
Tumble starts Saturday night at 6:30PM on BBC One.
Browse pictures of the stars below...