Showtime was nearing as four men hopped out of their SUV, walked swiftly through a heavily guarded back door, and into a top-secret rehearsal. It was the day of the 2013 MTV Video Music Awards, and 'NSYNC had to finalize their surprise performance without anyone finding out.

During "VMAs Revealed," which aired today on MTV, producers and behind-the-scenes staff explained how the whole stunt was pulled off. At first, Justin Timberlake said nothing to show-runners. While rehearsing on six different stages, he left one stage out, only blocking out small amounts of choreography during practice. At last minute, Timberlake's team let very few people in on the secret -- he was bringing back the band, but no one knew until they emerged through the stage's trapdoors that very night. Watch the behind-the-scenes clip below.

The 'NSYNC reunion went off without a hitch, but hours before the show, the KAWS-designed stage broke down. The skull-shaped stage was supposed to rotate to reveal different acts throughout the night, but turns out, it wouldn't rotate at all. With minutes ticking down until Lady Gaga's big opener, stars like Drake and Miley had to rework their performances, leaving everyone backstage in a scurry, as the clip below reveals.

Keep it locked in to MTV throughout the day Saturday while VMA performers 5 Seconds of Summer pop in and out to share "100 Things About The VMAs" until 8 p.m. ET/PT. And of course, watch the big show on August 24 at 9 p.m. ET/PT for more craziness.