The criticisms are rolling in like thunder clouds for Justin Bieber, who Jon Bon Jovi slammed for delaying a concert.

The rock star, 51, told the London Evening Standard in a recent interview in Vienna on his Because We Can world tour that Bieber was an "a**hole" for starting his show two hours late at the O2 arena in March. The teen star risks "alienating fans" if he does not get his act together, Bovi said.

Bovi, who many believe is one of the hardest working singers in the music biz, said that many young stars show up late to shows a lot. "Every generation has guys that do that, none of that is new."

What is also not new is Biebs having to cover his tracks and missteps. The singer blamed the lateness on "technical issues" and claimed it was a 40-minute postponed show.

But Bovi disagrees. "They run the risk of disrespecting their audience who have worked hard to pay for their ticket, to give you the permission to take two or three hours of their lives - or in that kids' case 80 minutes of their lives."

He went on to say that being late once warrants forgiveness, but many times is shameful. Then, he went in on Bieber, cursing him and saying he should go to "f**kin" work.

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And watch a video report on Bovi's diss below!