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The 18-year-old heart-throb kicked off the US leg of his “Believe World Tour” Leaving his mark in Arizona… literally.

Bieber was in the middle of his rendition of “Out of Town Girl,” where he ran suddenly turned his back to the crowd, bent over and literally threw up on stage. He then ran off stage while his dancers moved along and a tyhe mess was cleaned up.

He returned to apologise to fans, “I’m sorry, I’m going to slow things down” before launching into an acoustic of “Fall.”

A few numbers later, the “Baby” singer ran off-stage during a pre-recorded performance of his Nicki Minaj-assisted “Beauty and the Beat,” only to emerge with more apologies. “It’s hard for me, you know, not feeling great and throwing up in front of a bunch of people,” he said. Bieber then asked the thousands of Beliebers in attendance if they still loved him even if he was throwing up onstage to which he received an emphatic “Yes!”

Bieber later tweeted that “Milk was a bad choice,” citing the dairy product as the culprit for his messy show.