Maks Chmerkovskiy has been injured and has to sit out of tonight's Dancing With the Stars, and may have to sit on the sidelines for even longer.

Heather Morris will have to dance with a new partner on Monday night's live episode of Dancing With the Stars. Chmerkovskiy, her partner, can only watch from the sidelines now after hurting himself in rehearsals for this week's show.

ABC's Good Morning America broke the news that Chmerkovskiy wouldn't be dancing tonight, showing exclusive rehearsal footage of the incident.

"It's my calf muscle," Chmerkovskiy says in the clip. "F---. It just feels like something hit it."

Dancing With the Stars troupe member Alan Bersten will step in to dance with Morris tonight.

The Good Morning America hosts discussed Chmerkovskiy's injury, with Robin Roberts saying she hoped the injury was not on his Achilles heel.

"From all the athletes and football players that have done this show, they've all told me it is the hardest thing they've done," Michael Strahan added, of the toll Dancing With the Stars can take on your body.

It remains to be seen if this injury will slow down Morris' momentum as a possible frontrunner to win the Mirrorball trophy this season. The Glee star came in with a bit of an advantage over her fellow celebs considering her extensive dance and performance background. However, Morris and DWTS judge Julianne Hough have insisted that ballroom dancing is a different animal compared to her prior experience.

Morris and Chmerkovskiy's first dance was a Vienesse waltz set to the song "Make Something Beautiful" by Ben Rector. Each of the four judges (Hough, Carrie Ann Inaba, Len Goodman and Bruno Tonioli) gave them a "7", for a total of 28 out of 40. This put them in a tie for third place on the leaderboard, behind Simone Biles and Sasha Farber and David Ross and Lindsay Arnold.

Dancing With the Stars season 24 airs Mondays at 8 p.m. ET/PT on ABC.

Tags: Dancing with the Stars Reality TV ABC