Unable to get a Conor McGregor rematch, Jose Aldo's camp is growing frustrated with what they perceive as UFC bias.

Aldo's coach Andre Pederneiras told Sherdog.com that McGregor's upcoming lightweight title shot against Rafael dos Anjos is the kind of opportunity that was not afforded to his fighter.

"Concerning Aldo, we are just waiting to see what the future holds right now since McGregor has been allowed to keep the 145 title while being able to fight for the 155 title," Pederneiras said, according to Lewis Mckeever of Bloody Elbow.com. "That is something that hasn't happened before. I spent four years asking the UFC the same thing, to allow Aldo to keep his featherweight belt while going up and contesting at lightweight but it was never allowed. Now we see Conor get the OK on his first request."

The closest Aldo came to moving up for a superfight was a pair of missed opportunities with lightweight Anthony Pettis. A fight was actually booked between the two for UFC 163 in August 2013, though that was before Pettis won a title. Pettis eventually pulled out with a knee injury.

After Aldo defended his title against Ricardo Lamas at UFC 169, he again mentioned wanting to fight Pettis, who, by that time, had become lightweight champion. Instead, Pettis was selected to coach on season 20 of "The Ultimate Fighter" opposite Gilbert Melendez.

Aldo has also suffered various injuries that have limited his matchmaking options for the past few years.