Spokeswoman Jana Davidoff said the "Sex and the City: The Movie" actor sought medical attention Friday after feeling sharp groin pains, People.com reported.
Davidoff said Marini, who is paired with professional dancer Cheryl Burke on the ABC series, was diagnosed with tendonitis in his groin and shoulder.
Despite that diagnosis, Davidoff said the 33-year-old actor should be ready to perform on the series' March 9 premiere.
"We're pretty confident he'll be fine for premiere night," Davidoff told People.com. "He's in great shape. He'll be fine."
The Web site said Marini's fellow celebrity contestant, pop singer Jewel, is also expected to appear in the eighth season premiere despite suffering a knee injury this week.