"I was like, 'What? No. You're kidding, right?' He goes, 'No, I'm serious,'" she told Good Morning America. "And my first thought was, 'There's no way.' I don't pay attention to Pat."
"I'm busy with my letters and my puzzle board," White joked. "I mean, I'm hearin' him, but I don't really pay that much attention."
She added she was "terrified" but "did it."
"[You] have to be aware of everything that's going on, where before all I had to worry about was letters," she explained. "Now I have to carry the whole show, I have to talk to all three players and make sure I get their scores right."
White will be hosting for three weeks while Sajak recovers from his emergency surgery.
The 73-year-old beloved leader of "Wheel" left a taping in early November after suffering from intense stomach pain.
"Our taping on Thursday was canceled because host Pat Sajak underwent successful emergency surgery to correct a blocked intestine," the show's Twitter account confirmed on Nov. 8.
"He is resting comfortably and looking forward to getting back to work," the statement said.
White said the moment she learned about her friend's health issues was "horrible."
"We've been together 37 years, and it's not the same -- we are a team," she said. "We're together. It just felt weird with him not being here on the set. You think the worst because you never know when you're going in for surgery. You never know what's going to happen."
White previously filled in for Sajak in 1996 when he suffered from laryngitis.
"I just can't imagine doing this show without him, you know?' she said. "And I hope he feels the same with me."
So, with White filling in for Sajak, who is taking over her duties of turning the letters?
That's still not official, but the game show has partnered with Disney for a “Secret Santa Holiday Giveaway," so expect a few familiar big-eared faces.