Fans weren’t far off with their speculation of what caused Justin Bieber and Usher‘s recent confrontation…

As we previously reported, the pop star and his former mentor have had a rocky relationship for some time now. Justin and Usher unfollowed each other amid all the Diddy allegations that were coming out. Usher also allegedly helped Diddy get “control” of the Canadian artist back in the day, per some wild claims from the time. And it all seemed to have come to a head at Beyoncé and JAY-Z‘s Oscars afterparty last week.

The pair were reported to have gotten into a “heated argument” when they came face-to-face at the party. And now, per DailyMail.com, we know the reason why. According to a source, their disagreements reached a “boiling point” this past week, as Justin believes Usher didn’t protect him during his early career — but the OMG singer thinks Justin “under-appreciates” the work he did for him.

Related: Inside Justin’s ADORABLE Birthday Celebrations With Hailey

A party insider said Justin brushed off Usher “the same way he has for a while now” which resulted in the 47-year-old getting angry:

“From his perspective, there’s a level of loyalty and gratitude that hasn’t been reciprocated, and the distance between them has come off as dismissive and disrespectful. Usher, who played a key role in helping Justin get his start, feels that history matters.”

But they also said JB “feels taken advantage of and has some disdain for his past management” AKA Scooter Braun:

“There’s always been tension after Justin blew up.”

A second insider added that “it’s baffling” Usher doesn’t understand this:

“Usher was around from the beginning, ever since Justin was a kid.”

Wow. We can’t say it’s exactly unexpected, all things considered… But what do U think, Perezcious readers? Let us know in the comments (below).

[Image via MEGA/WENN]

The post REVEALED: What Sparked Usher & Justin Bieber Confrontation At Beyoncé's Oscars Party, Per Source appeared first on Perez Hilton.