But any reservations she may have had based on his appearance were quickly lost when Derek showed amazing calm under pressure, helping Jennie overcome an awkward fall during their second dance together.
"I think it was quick step, and it went really well, and we were sort of flying by the seat of our pants," she recalled. "We had this great move planned for the end, and it was very exciting. Very like brave of us, and we did it, but we didn't account for the dress, and the dress just sort of slipped right under his shoe."
And so went "The Fall" as show fans have dubbed it. Both dancers ended on the ground, but Derek was the first to spring up and offer a mortified Garth his hand and reassuring words.
"I said, 'You know what? Do not worry about this; I've already got a plan. I know next week you're going to come back, we're going to tango, and you're going to do amazing,'" Derek said. "And she did."
He's right. Though they stumbled out of the gate, they've been waltzing with the judges and audience ever since, often winning scores of perfect 10s as they step lightly toward the finals.
Meanwhile, Julianne is also nearing the checkered flag with a very spunky race car driver who has control issues.
"I love racing because [with] racing you have to be in control," explained Castroneves, a two-time Indy 500 winner and the youngest to achieve this feat. "But here, I'm not in control of this machine."
For her part, Julianne has taken to the driver's seat very well, working diligently with Castroneves to pull off crowd and judge-pleasing routines each week, while still managing to have fun and yes, amazing chemistry, with a second dance partner. Although she's been known to go wild on them from time to time, something to which her old partner can attest. Castroneves has reached out to Ohno via text message during the season to get feedback and advice on how best to work with the "race car" that is Julianne Hough.
"OK, Julianne is becoming a little wild. What do I do?" recounts Castroneves of a message he sent Ohno. "He'd be text messaging me, 'Great, keep on doing what you're doing,'" he said. "'That's the way she is -- happened to me as well.'"
Castroneves is hoping that a "Dancing With the Stars" win will "happen to him," just as it did for Ohno with Julianne in control of their partnership last season. The rhumba they danced together this week to the usual applause and judges' praise suggested they were on the right track to get there. Derek and his ever-improving partner Jennie Garth are on the same track, however. Which sibling makes it to the finish line first -- if at all -- remains to be seen. But in the eyes of millions of fans, especially their parents, the dancing siblings from Utah, by way of London, are equally fantastic.
Julianne and Derek will both participate in a "Dancing with the Stars" tour, starting this December in Seattle. Click here to learn more.