Justin Bieber singing acoustic version of his song Fall on his Believe Tour.

Justin Bieber singing acoustic version of his song Fall on his Believe Tour.

Justin Bieber’s Believe Tour is getting unbelievable. The singer’s latest stop in San Jose, Calif. June 26, proved to be a bit of an embarrassment for him after he admitted he forgot some of the words to one of his own songs during a performance.

“San Jose was right tonight. I might of forgot the words to Fall for a second there. Things happen. Lol,” the 19-year-old singer Tweeted afterward.

Bieber’s behavior has become more and more erratic of late. On Monday, (June 24) he posted a short video of himself on Instagram making fun of the fact that he suffered scrapes and bruises from falling down a flight of stairs.

“If u didn’t hear I fell down the stairs this morning. Check my Instagram for details. It was epic :) lol,” he tweeted. Bieber seemed a little out of it.

The move came after a tabloid report that Bieber’s long-time manager Scooter Braun was desperate to get the singer into rehab because of multiple incidents involving marijuana, wild parties and brushes with the law.

In the latest development, photographer Osmin Hernandez Duran filed a lawsuit claiming that Bieber gave him a karate-style kick in the stomach and punched him in the face outside a movie theater in Calabasas, Calif. He was with then-girlfriend Selena Gomez.

Bieber claimed the paparazzo was blocking his car and wouldn’t move. It was one of a string of run-ins with photographers.

As for rehab, both Bieber and Braun called the story false.

At the concert Justin was playing the guitar and singing an acoustic version of the song with a backing guitarist when he stumbled over the words. He was perched on an elevated platform. He performed the song in San Diego three days earlier without a mistake.

Atlhough he later acknowledged his mistake, he never appeared to miss a beat. And, he was at least singing live.