Justin Bieber cancelled his Portugal concert Tuesday -- not because he's sick, not because he's melting down -- because ticket sales were "soft" and it felt like the right thing to do. Just tell that to the fans who are getting stood up.
Sources connected to Justin have confirmed ... it was a "business decision" that triggered the cancellation. Our sources say ticket sales were still "good ... more than 60%" ... just not good enough.
It's pretty common for lesser artists to bail when sales are bad, but unusual for signer's on Justin's level.