Dancing With the Stars Recap: Katherine Jenkins Melts Down—and Needs a Doctor—After the Salsa!

What threw the normally poised opera singer off her game? And who vaulted back on top?!

Dancing With the Stars got dicey tonight.

It was semifinals time Monday for the four best contestants from what right off the bat has been an unusually strong season: Donald Driver, Katherine Jenkins, William Levy and Maria Menounos.

Then again, the judges have been pretty stingy with the perfect scores, handing out only two 30s beforehand, so every kick, flick and turn can mean the difference between a spot in the final round and going home—or, as was the case tonight, going to the doctor.

So, just how close was this penultimate performance show?

"To get into the finals, you have to bring your A-game, and I don't think you did that," Carrie Ann Inaba told Katherine sternly. "You brought your A-plus game!"

So that's how the judges were going to play it tonight! And yet, despite an overall wave of praise for the quickstepping singer, Len Goodman put a damper on the first-round party with a 9.

William's first dance, a tango, met a similar fate, being adored by Bruno Tonioli but picked over a little more by Bruno and Carrie Ann for an ultimate 28.

Donald was saddled with two 9s despite a waltz that looked picturesque from every angle. Once again, Carrie Ann and Len spotted the missteps, and Bruno just enjoyed every second of it.

In fact, the boisterous Italian handed out nothing but 10s in the first round! But it was only Maria and Derek Hough's Argentine tango that merited "from Len, a 10" in round one.

We caught a couple of teeny hand fumbles in William and Cheryl Burke's samba, but they joined the perfect-30 party to kick off round two. And it looked as if Katherine was about to join them...

But when she appeared to run out of gas during some physically taxing floor work during her salsa, she missed the final turn and stumbled, rather than land on Mark Ballas' ready-and-waiting knee.

The Welsh beauty immediately covered her hands with her face and appeared to be shuddering as Mark soothed her, saying, "I've got you," and Tom Bergeron assured her there was no reason for her to apologize.

The judge understandingly cut her some slack in their critiques, but she was unable to join the perfection club tonight. (You could tell, though, that they wished they could just give her three 10s.)

"I just felt my back go as I bent back," Katherine said tearfully backstage. "I'm so sorry if I've let you down, Mark." Then it was time for the doctor to come and check her out.

It was hard to shake that off and focus on Donald and Peta Murgatroyd's samba—but we managed. And though Len remained stubbornly in single digits, the Super Bowl winner managed two more 10s.

Maria and Derek closed the show with another intricately choreographed routine, this one a jive that was almost perfect.

"It's all him!" Maria raved about her partner. "I put hard work in, I definitely did, but I would never be this good. I was never get 10s without Derek Hough!"

Here's how the leaderboard stacked up:

Maria Menounos and Derek Hough: (30+29) 59
William Levy and Cheryl Burke: (28+30) 58
Donald Driver and Peta Murgatroyd: (28+29) 57
Katherine Jenkins and Mark Ballas: (29+27) 56