Chris Pizzello/Invision/AP

Lin-Manuel Miranda introduced a song medley, and it appeared it was just another compilation of songs in movies that have had an impact.

But then ... Eminem came on stage to perform "Lose Yourself" and received a standing ovation from the crowd.

Although those at home seemed torn. Some took to Twitter to praise the performance and some were shaking their heads as to why he was there.

Either way, it was a moment.

Eminem himself took to Twitter to explain. "Look, if you had another shot, another opportunity... Thanks for having me @The Academy," he wrote, adding, "Sorry it took me 18 years to get here."

In 2003, "Lose Yourself" won the Academy Award for best original song in 2003. Eminem did not attend the awards show that year.