Manny Pacquiao still has designs on a rematch with Floyd Mayweather Jr after dropping a unanimous decision in their May 2015 super fight.

Pacquiao, boxing's only ever eight-division champion, will end a short-lived retirement from the sport when he challenges Jessie Vargas for the WBO welterweight title in Las Vegas in November.

The 37-year-old bounced back from his defeat to Mayweather, after which he required surgery on a torn rotator cuff, by comprehensively out-pointing Timothy Bradley in the rubber match of their trilogy in April.

The notion of that being a farewell fight was shelved soon enough and Pacquiao believes Mayweather could also be tempted into a ring return.

Freddie Roach, the long-time cornerman to the Filipino icon, believes Pacquiao's best division might be the 140lbs light-welterweight category, which would bring a showdown with rising American star Terence Crawford into view.

Crawford is viewed in some quarters as the natural heir to the supreme stylist Mayweather, but there remains a sense of Pacquiao having unfinished business with his contemporary.

"I can still fight at 140 – 140 or 147. I'm willing to fight anybody," he told Omnisport.

"If [Mayweather] wants and the fans want to have that fight again, then why not?

"That can be a very exciting fight. There's no reason why [it cannot happen]."

Contrary to popular opinion, Pacquiao believes he edged the initial encounter and would not want to leave a semblance of doubt in any Mayweather revenge mission.

"I know I really need to win clearly," he added.

The ever-ostentatious Mayweather has floated the idea of meeting similar bombastic UFC superstar Conor McGregor in the event of him making a comeback to action, but the cross-codes clash does not hold any particular intrigue in Pacquiao's eyes.

"It depends because McGregor is an MMA (mixed martial arts) fighter. If the fight is in boxing rules, McGregor is no match for Floyd Mayweather," he said.

"But if the fight is MMA rules, then Mayweather is no match for McGregor."