(CNN) -- Manny Pacquiao's career will be defined by Floyd Mayweather, even if the Filipino can't give boxing the fight it has long been clamoring to see.
That's the view of Sports Illustrated's boxing correspondent, Bryan Armen Graham.
He says he is optimistic that Pacquiao and Mayweather can finally reach a deal to settle who is the best pound-for-pound fighter in the sport.
Pacquiao's next fight is in May next year while Mayweather is due in court next month to answer charges of domestic violence. Should he retain his liberty, Graham thinks a showdown in December 2011 is a possibility.
And according to Graham, the danger for eight-division world champion Pacquiao is that his legacy will be affected just as much by a failure to meet Mayweather in the ring than if the fight goes ahead.
He told CNN: "If Manny gets through his next fight scheduled for May 7 and if Floyd resolves his problems I think there is actually a good chance. I'm as optimistic as I have been in long time for that fight to come off late in the year, maybe December.
"But the truth is there are a lot of theories about Floyd maybe waiting for Pacquiao to be past his prime, like Sugar Ray Leonard did with Marvin Hagler in the eighties.
"Manny Pacquiao, I think he is a once in a generation type talent. I know there are people calling him greatest of all time and you always kind of rush to judge these things when you see someone so spectacular in their prime.
"Its really unprecedented what he is doing but I think we are probably going to have to wait until all is said and done until we really make judgments on his career.
"One thing for sure though is if the Floyd Mayweather fight doesn't happen he [Pacquiao] might be defined just as much for not having that fight."
Pacquiao, who is a congressman in the Philippines, is due to announce who his next opponent will be at his 32nd birthday celebrations on Friday with Shane Mosley, Juan Manuel Marquez and Andre Berto in the frame.
Graham explained: "There is Shane Mosley, the former WBA welterweight champion, Juan Manuel Marquez, the current WBO lightweight champion, and a dark horse candidate is Andre Berto, the former Olympian, who is undefeated but has not really fought anybody of note and has the lightest resume of the three.
"[Mosley] is the best known but at the same time he is also coming off two really bad performances. He lost 11 of 12 rounds against Floyd Mayweather in May and he had a very, very listless controversial draw [with Sergio Mora] in September.
"He is 39-years-old and he probably doesn't deserve a shot against the pound-for-pound champion, but deserves seldom has anything to do with it in boxing."
Pacquiao made history by becoming the first fighter to claim titles in eight weight divisions after his victory over Antonio Margarito secured the vacant WBC super-welterweight belt.
According to reports in the Philippines, Pacquiao is currently ironing out a query over his taxes arising from fights in 2009. He recently moved his next fight from April to May due to his political responsibilities in the country.