The force was strong at the 2015 American Music Awards. The a cappella group Pentatonix performed a "Star Wars" tribute along with John Williams' orchestra at the awards show in Los Angeles Sunday night, in yet another promotion for "Star Wars: The Force Awakens."

Harrison Ford, who plays Han Solo in the "Star Wars" films, introduced the group. "Many of you know composer John Williams' name, but one thing for sure all movie fans know for sure: this music," Ford said. He then had the "Jaws," "E.T." and "Indiana Jones" themes play. He then told the audience to prepare for the music from "Star Wars" in a way they never heard before.

Pentatonix took the stage dressed in "Star Wars" costumes, while scenes from the films played out on screens behind them. First, the group sang the "Imperial March" by themselves, but soon Williams' orchestra kicked in behind them.

Watch the full Pentatonix performance below:

Pentatonix is an a cappella group from Texas who got their start when they won the third season of NBC's "The Sing-Off." Prior to Sunday's AMAs, Pentatonix's Kevin Olusola told Rolling Stone the band was excited to perform with Williams' orchestra. 

"Our background is in choral music, so this felt like a chance to revisit and re-study certain classical techniques. It sounds so amazing," Olusola said. "Our fans are going to be geeking out, because a lot of them are choral students, and I think they're going to get a huge kick out of this."

"Star Wars: The Force Awakens" hits theaters Dec. 18.