Timothy Bradley insists the prospect of a lucrative third fight with boxing great Manny Pacquiao is not on his mind as he prepares for Saturday's exciting welterweight title showdown with Brandon Rios.

Filipino fighter Pacquiao, the only man to have won titles in eight different divisions, is set to get in the ring one more time before retiring to focus on his political career.

Hall Of Fame promoter Bob Arum has earmarked Bradley as one of three potential candidates for Pacquiao's farewell, with fellow American Terence Crawford and British star Amir Khan also in the frame.

It would mark the third time Bradley and Pacquiao have gone head-to-head, with the former winning by a controversial split decision in 2012 before the latter comprehensively won the rematch in April 2014 to hand Bradley his first loss.

But Bradley, who has 32 career wins with 12 by knockout, has parked any thoughts of facing Pacquiao for the time being, because he is aware that any complacency will prove costly when he defends his WBO belt against the all-action Rios in Las Vegas.

"I'm really not thinking about it [facing Pacquiao]," Bradley told The LA Times. "It hasn't even been a thought.

"I know [a third fight] is realistic, but th opportunity can't be there unless I beat Rios. I can't think about the opportunity, because the opportunity I have in front of me is the only thing that's important. So Pacquiao hasn't even crossed my mind."

Bradley is the favourite to defend his belt, but comes up against a re-energised Rios, who saw his blossoming career stalled by back-to-back defeats in 2013.

Rios won his first 18 fights and, after a controversial draw with Manuel Perez in 2008, also had his hand raised in the following 13.

However, he was beaten on unanimous decision by Mike Alvarado before being completely outclassed by Pacquiao when his chance to fight the best arrived.

The American rebounded by defeating Diego Chaves and Alvarado as the pair completed their trilogy, and the 29-year-old concedes that he took his eye off the prize against Pacquiao.

"You reach a point in your career when you mature, stop being a little kid and think of the future," Rios, who has 33 career victories, told Yahoo Sport. 

"I got big-headed and stupid. I was making a lot of money as a young kid. I never had money before, and that had a lot to do with it. I just had to re-light the fire that has always been in me, that's been in my heart."