For the first time on the show, each celebrity and his professional dance partner will be required to perform three numbers. Both couples will dance the samba and a freestyle, then for their third dance, Smith and partner Cheryl Burke will do the mambo while Lopez and partner Karina Smirnoff will perform the paso doble.
"I'm very nervous," says Burke, 22, who won the season 2 title with celebrity partner Drew Lachey. "Emmitt, on the other hand, is very cool. We balance each other out."
Smith says his years with the Dallas Cowboys have prepared him well for the kind of pressure and scrutiny Tuesday night will bring.
Lopez, who has been teased throughout the season for having a short attention span and a fiery on- and off-screen relationship with Smirnoff, is a bit giddier. "I'm going up against Emmitt Smith! He was like a hero of mine!" Lopez tells PEOPLE, noting that he thrives on stress. "I'm a hyper, energetic person and I like to keep busy and do a bunch of other stuff. I think I work best under pressure."
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He praises his wife, Pat, for being his faithful teammate. "She has made our home very happy and the kids feel love in the house. When Daddy is away, they know Daddy is coming back."
Lopez's mother, Elvia, has been in the audience each week to support him, as have a slew of celebrity pals including Eva Longoria, Jose Canseco, George Lopez, Oscar de la Hoya and Elizabeth Berkeley.
Lopez jokes that he is "withering away" – down three belt notches thanks to daily eight-hour dance rehearsals. What he's looking forward to most when it's all over is "just chilling." And eating. "My mom will be cooking and I'm visiting my sister over (Thanksgiving) and she'll be cooking. They'll take care of me."
Burke, meantime, confesses that while the end is near and "I really want that trophy," she's already stressing about what's next. "I'm going to miss Emmitt," she says. "I'm already missing him."
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But first, there's a trophy to win. And bragging rights. "It's always been my philosophy: It's not where you start, it's where you finish," Smith says. "I want to finish strong."