*Alfonso Ribeiro’s “Dancing With the Stars” run could come to a premature end, thanks to a fresh back injury during rehearsals this week.

According to TMZ, the front-runner for Season 19’s Mirrorball trophy was trying to “over-compensate for a groin injury” he sustained during his performance of The Carlton Dance back in early October…

As of this morning, Nov. 14, the 43-year-old actor was still attending — but not participating in — rehearsals for his upcoming routine with pro partner Witney Carson. A source told Us Weekly he was watching Carson dance with a stand-in, and hoped to learn the steps visually. However, producers are “worried he could cause long-term damage to his back,” the insider said.

Ribeiro’s “Carlton” earned a perfect score from the judges, but its dramatic side-to-side swinging left him in excruciating pain. “I hurt my groin doing the Carlton,” he shared two weeks later. “I think I did it so hard that I actually pulled it.”

Despite that, Ribeiro continues to be one of the best dancers in the competition, and is consistently among the top-scoring couples week after week. He earned his second perfect score just a few days ago on Nov. 10, for a paso doble he and Carson did with fellow “DWTS” pro Lindsay Arnold to DJ Snake and Lil Jon’s “Turn Down for What.”

After the performance, judge Carrie Ann Inaba gave him a standing ovation, and Bruno Tonioli called it “the ride of the night.”

If Ribeiro does end up leaving, the race for the Mirrorball will be down to four: “Duck Dynasty’s” Sadie Robertson (and partner Mark Ballas), YouTube star Bethany Mota (and partner Derek Hough), comedian Tommy Chong (and partner Peta Murgatroyd), and “Pretty Little Liars” actress Janel Parrish (and partner Val Chmerkovskiy).