Jennifer Garner Reveals Why Mark Ruffalo 'Almost Dropped Out' of '13 Going on 30'

The pair co-starred in the beloved 2004 film.

Mark Ruffalo almost didn't get to show off his best "Thriller" dance moves! Ruffalo's 13 Going on 30 co-star, Jennifer Garner, revealed to theSkimm that the 53-year-old actor was not a fan of dance rehearsals for the 2004 film. 

In one famous scene, Garner's character, Jenna Rink, convinces a whole party of adults to do the iconic dance to Michael Jackson's "Thriller." 

"Our first rehearsal, I think it was Mark and Judy [Greer] and me, and Judy and I were both dancers growing up and poor Mark didn't know that," the 48-year-old actress shared. "And he came in and he hated the rehearsal process so much he almost dropped out." 

Garner and Ruffalo, who played love interests in 13 Going on 30, have teamed up again, this time in the upcoming film, The Adam Project. 

"It was wonderful," she said earlier this month of reuniting onscreen with Ruffalo. "We were playing a married couple and we just had this instant comfort and obviously there's just such a connection and a warmth. It was actually a really beautiful experience to revisit that relationship."