There may be a notable professional dancer missing from tonight's episode of "Dancing with the Stars." Mark Ballas, who is partnered with UFC fighter Paige VanZant, injured his back during rehearsals for the show Sunday night.

Ballas, 29, may have to sit out of the dancing competition due to the nature of his back injury, which has been a problem for the dancer in the past. While it has not yet been revealed how serious the injury is, VanZant has been practicing with dancer Alan Bernsten, who is a member of the "Dancing with the Stars" touring troupe.

"Mark has been so supportive and just a lot of fun to work with," VanZant said after last Monday's premiere episode. "I don't know how I'd do this without him."

A photo posted by markballas (@markballas) on Mar 21, 2016 at 6:17pm PDT

"He injured his back at camera blocking rehearsal on Sunday," a source said of the professional dancer. "It's an old injury that he aggravated. It's up in the air if he'll be able to perform tonight." The source then continued to say that Ballas' fate would be decided by a doctor later in the day.

Season 22 of "Dancing with the Stars" has only been underway for two weeks now, but Ballas' injury is not the first one of the season. Last week, deaf model Nyle DiMarco was sent to the hospital and had to get stitches during rehearsal when he was elbowed in the eyebrow by his partner Peta Murgatroyd.

During Ballas and VanZant's first week of the dancing competition show, the two wowed the judges and earned 21 out of 30 points for their fox-trot. Ballas joined the show during Season 5 and has won the competition twice - with Kristi Yamaguchi in Season 6 and with Shawn Johnson in Season 8. He has taken second place twice (with Katherine Jenkins and Sadie Robertson), but only managed to place in sixth last season with actress Alexa PenaVega.

Ballas has been hurt on the show before, but he did not let his injury impair his dancing abilities during Season 18 when he injured his shoulder.

"Dancing with the Stars" airs Mondays at 8 p.m. ET on ABC.