By Breaking Celebrity News Staff

Monday's was a bittersweet edition of Dancing with the Stars: All-Stars, as one celeb contestant soared to a perfect 30-point total -- in spite of a dramatic injury to their partner -- as the night was salvaged by the sweet steps of a ready replacement.

SPOILER: Who’s Perfect & Who’s Hurt?

Shawn Johnson's been partnered with Derek Hough, but the three-time champ was sidelined with a neck injury -- specifically, a bulging disc in his vertebrae -- opening the door for Mark Ballas to step in.

The week's twist was that the contestants had to fuse together two different dances; the change in partner was seamless for the Olympian, who got 30 points for her fusion of tango and paso doble with Ballas.

Judge Bruno Tonioli complimented Shawn on her "flawless fusion" and "maximum purity of each dance."

As for Derek, a source told US magazine that his "injury is really serious" and that "it's likely Mark will finish out the season for him" following the elimination of Mark's initial celeb partner this year, Bristol Palin.

"Derek is so disappointed but very badly hurt -- he needs surgery."

For the single dances, the full totals were: Johnson and Hough (30); Melissa Rycroft and Tony Dovolani (29); Gilles Marini and Peta Murgatroyd (28.5); Emmitt Smith and Cheryl Burke (27.5); Apolo Anton Ohno and Karina