Justin Bieber is learning the importance of being on time.

The pop star was late to his London concert earlier this week, and now reports say that his tardiness was due to his own diva-like behavior, according to The Sun.

"He was arguing with members of his management, his family," says a source about his behavior prior to the start of the show. "It was a really uncomfortable atmosphere."

"His attitude was, ‘I’m the star and I can do what I want,'" the source adds.

However, Justin is fighting back on Twitter, claiming that the rumors are untrue.

On March 6, he wrote: 

He also wrote a slew of other tweets about the situation, and he ended things by saying that he just wants to focus on the music.

So was Justin acting like a diva? We may never know.

If nothing else, we're guessing he'll at least try to work on his punctuality from now on.

Source: Twitter, The Sun