Justin Bieber explains why he broke down in tears at the VMAs

Justin Bieber got a little misty eyed after he sang and danced his heart out on stage at the MTV VMAs on Sunday evening.

The 21-year-old star performed his two new hits, "Where Are U Now" and "What Do You Mean?" When he was done, the star received a big round of applause that caused him to buckle over and wipe away tears, then break down.

Bieber was a guest on Jimmy Fallon's 'The Tonight Show,' and he was asked what made him so emotional on stage. Bieber replied that he was moved by the support he received from the audience, especially because the last time he performed at an awards show he was booed.

Bieber also says he missed some cues during the performance and felt disappointed, but he was relieved to see the crowd didn't care or judge him for it.

"Honestly, I just wasn't expecting them to support me in the way they did," Bieber told Fallon.

"Last time I was at an award show I was booed. I've worked so hard on this album. I've worked so hard at becoming the man I want to become. Stepping into situations, you just can't help but feel judged, so I was just feeling judged and just wanting to win so badly and wanting to do what I love so badly that I just put everything on the line. What was just so special about the emotional moment at the end; it was just authentic, it was real."

Bieber's new album is his first in three years. "What Do You Mean" reached the number one spot on iTunes within five minutes of dropping, which makes it the fastest song to reach the top of the iTunes charts ever.

Here's Bieber explaining his reaction at the VMAs to Fallon.