The blonde bombshell, 32, donned a blue dress with nude material underneath, showing off her famous curves.
The clingy material showed off Rachel’s perky derriere as she did the numbers and letters.
It didn’t take long for viewers to to compliment Rachel’s look on social media, as one posted: “Love that dress.”
Another added: “Rachel you’re beautiful.”
A third chipped in: “Hi Rachel, my wife is desperate to know where you got that dress from?”
A fourth wrote: “That dress is great.”
Rachel also appeared on The Jonathan Ross Show wearing a stunning red dress with a sheer mesh panel along the front, flaunting her assets.
She spoke to the Jonathan alongside Jack Whitehall, Ralph Fiennes, and singer Lizzo.
But the guest Rachel was most impressed with was Crufts champion pooch Dylan the Villain, who was also on the show.
She told her 365,000 followers: “I don’t normally like to name drop but I did get licked by this megastar this week!
“Spent a good hour with Dylan the Villain aka Crufts new reigning champion – he’s gorgeous!”
Countdown continues on Monday at 2.10pm on Channel 4.