Justin Bieber explains why he cried on stage and his reason will make you cry!

Los Angeles - Justin Bieber cried at the MTV VMAs because he was overwhelmed.

The 21-year-old singer broke down on stage during the performance of his comeback single What Do You Mean? on Sunday and admitted it was because he was so surprised by the support he received.

He told chat show host Jimmy Fallon: "It was just so overwhelming for me - everything, just the performance. I just wasn't expecting them to support me in the way they did. The last time I was at an awards show, I was booed. I think it's just like I've worked so hard at this album and at becoming the man I want to become, and then stepping into situations, you just can't help but feel judged.

"So I was just feeling judged and wanting to win so badly, and wanting to do what I love so badly that I just put everything on the line. And I think that that was what was so special about the emotional moment at the end, that it was authentic. It was real. I was really just wanting it so bad."

However, Justin admitted he wasn't completely happy with his performance, saying: "I missed some cues, so I was a little disappointed at that".

Watch the interview here: