Justin Bieber, 18, showed his star power this weekend at the kickoff of his hotly anticipated Believe tour in Phoenix, Arizona, when he got sick on stage but still powered through his entire act with only a few setbacks, admitting his condition at one point to the audience.

Bieber had stomach problems during the show and twice had to leave the stage to throw up, and didn't even make it the first time, doubling over and vomiting on stage during the performance of his track, "Out of Town Girl," about an hour into the concert, reports USA Today.

Bieber then walked off stage while the backup performers continued going. When Bieber returned, his fans greeted him with cheers, and he admitted, "I'm sorry, I'm going to slow things down." The next time he had to leave, he apparently made it in time so that his devoted fans didn't have to see the contents of his stomach spill upon the stage. The show ceased for a few minutes, and Bieber came back again, this time addressing the matter directly.

"It's hard for me, you know, not feeling great and throwing up in front of a bunch of people," he said. "Will you love him even though I'm throwing up on stage?" he rhetorically asked, but young girls answered with their enthusiastic screams, anyway. "Ok, I wanted to give you my best show ever, so do you mind if I finish it?"

At the end of the show, which included his "Beauty and a Beat" duet with a virtual Nicki Minaj, Bieber dedicated his "One Less Lonely Girl," and the entire show, to Avalanna Routh, the 6-year-old diehard Belieber who recently succumbed to her battle with cancer. "If you're listening," he said, looking up to the sky, "I love you."

Biber later joked about the embarrassing incident on Twitter, quoting Will Ferrell's character, Ron Burgundy, from Anchorman. "Milk was a bad choice! Lol," he said. "Great show. Getting better for tomorrow's show."

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