Manny has a record of 51 wins, three defeats and two draws from 56 fights
Manny Pacquiao will start negotiations with Antonio Margarito or Miguel Cotto after a deadline to agree a clash with American Floyd Mayweather Jr expired.
Pacquiao's promoter Bob Arum said talks with unbeaten Mayweather to arrange a bout for 13 November were now over, although the clash could still happen.
A fight with Mayweather for earlier in 2010 was called off over Pacquiao's failure to agree to blood testing.
"The fight we wanted is Mayweather, but he didn't want to commit," said Arum.
The pair are considered the two best pound-for-pound boxers in the sport and a fight between them would likely be the richest in history.
And after Filipino Pacquaio agreed to Mayweather's blood and urine testing requests in May it looked as if a fight between the pair would happen in November.
"I am sure, without knowing, that there is a very good reason why Mayweather hasn't committed at this time," added Arum.
Arum suggested that the issue over drug testing had been resolved and speculated that the pending trial of Mayweather's uncle and trainer Roger over a charge - which he has denied - of attacking a female boxer could be why the undefeated American would not agree to fight this year.
"I really believe this issue with the uncle has an affect," continued Arum.
"If I were in his shoes, I wouldn't want to go into this big fight without my trainer."
Pacquiao defeated Cotto (35 wins and two defeats) in November 2009 and could agree a rematch with the Puerto Rican fighter or take on Mexican Margarito (38-6), who has only just returned to the ring after being banned for a year for wearing illegal hand wraps.
Arum said he expected it to take only a week to negotiate a contract with either opponent, both of whom fight in his Top Rank stable.
"I have to discuss with Manny to see who he prefers. The decision falls on Manny," stated Arum.
Arum also suggested that Pacquiao could fight Mayweather in 2011, although the Filipino who has just been elected into congress in his homeland said in May that he would only fight once more.
Mayweather refused to discuss the likelihood of him facing Pacquiao when asked at a charity basketball game in Miami on Sunday.
"I'm not interested in rushing to do anything... I'm not really thinking about boxing right now," he said.
"I'm just relaxing. I fought about 60 days ago [against Shane Mosley], so I'm just enjoying myself, enjoying life, enjoying my family and enjoying my vacation."