Cody Linley and Edyta Sliwinska, Dancing with the Stars

Cody Linley, the only celebrity in the history of Dancing with the Stars to have to dance with a substitute partner, says he won't know until Wednesday when he'll be able to dance with pro Julianne Hough again. "We just don't know if she'll be up to it this week," he says.

Hough had to temporarily bow out of the competition last Tuesday to have laparoscopic surgery to remove her appendix and cysts on her ovaries, both complications of endometriosis. Hough herself estimated that she would be off the dance floor for two weeks. "She's doing great, but she was in a lot of pain [after surgery]," reports Hough's brother, Derek.

Linley, the 18-year-old Hannah Montana star, put on a brave face as he danced with another gifted pro, Edyta Sliwinska, but behind the scenes, he says, he wasn't coping well. "It was literally the hardest week of my life," he says. "I've never been under such physical and emotional stress."

Sliwinska, the only professional to have danced on the show all seven seasons, understands how difficult it's been on the young star. The pair had to perform two dances, without the benefit of the shorthand that the other couples have developed. "It was a really tough week," says Sliwinska. "Because at this point in the competition, people know each other so well, they know how each other move. It makes it so hard to come in with somebody else."

And being a substitute teacher wasn't the only challenge, says Sliwinska. "I'm really beginning to believe that this season is cursed," she says, referring to the unusual number of injuries. "Because the minute we started to rehearse, I got a huge blister on my foot from new shoes. So I had to rehearse in my socks for the whole week."

Read Mickey's recap of Monday's performances here and watch clips and full episodes of Dancing with the Stars in our Online Video Guide