Pacquiao is campaigning for votes in the Philippines
Floyd Mayweather has said he could be tempted to step up to light-middleweight to fight Sergio Martinez instead of taking on Manny Pacquiao.
A proposed fight between Mayweather and Pacquiao scheduled for 13 March fell through, since when both fighters have added further wins to their records.
After beating Shane Mosley on Saturday, Mayweather said fighting Martinez could now be an option.
"I thought about it. Right now, I don't know what I'm going to do," he said.
Martinez's manager, Lou DiBella, told the BBC he doubted a super-fight between American Mayweather and Filipino Pacquiao would occur, with the boxers unable to agree on the drug-testing programme or financial split.
DiBella argued it made more sense for Mayweather to fight Martinez, who recently defeated Kelly Pavlik for the WBC and WBO middleweight titles but is a career light-middleweight.
Pavlik would first have to waive his right to a rematch with Martinez, which was a clause in their fight contract.
However, Mayweather, who is now unbeaten in 41 fights, said a fight with Pacquiao could still occur if an agreement could be met on random drug-testing.
After the fight with Mosley, Mayweather said: "If Manny takes the [blood] test, we can make the fight happen."
Pacquiao is preoccupied with a different fight altogether - he is campaigning to be elected to the senate in his homeland of the Philippines.
The election is on 10 May and the 31-year-old is unlikely to make any announcement about his fighting future before that contest is over.
Mayweather (left) overcame Mosley despite an early scare
Pacquiao's promoter, Bob Arum, said: "I'm not going to lose any sleep over it. What I'm concerned about right now is Manny winning the election. If the fight doesn't happen, it doesn't happen. We're not going to be dictated to."
One option for Pacquiao would be a fight with WBC welterweight champion Andre Berto, who pulled out of a fight with Mosley in January after the earthquake which devastated his parents' homeland of Haiti.
Berto, a big puncher, stopped Carlos Quintana last month to retain his title, and he relishes a fight with Pacquiao.
Berto said recently: "He lacks defence. He's easy to hit, but he sets a pace that's a little too much for his opponents and he's incredibly strong, also, so he always tends to outwork and outpunch his opponents."
Andre Berto could be an alternative opponent for Pacquiao
The Mayweather-Pacquiao fight is the one the fans want to see and could be the most lucrative fight in history, with each fighter potentially picking up purses of $25m.
But DiBella said: "If both fighters are demanding 50% of each other then it makes more sense for both of them to take a fight with someone where you can get 80 or 85%.
"Mayweather-Pacquiao is clearly the most enormous fight out there but it wouldn't surprise me if they don't go in another direction."
DiBella said he anticipated Arum would seek to put Pacquiao in with another Arum-promoted fighter, either Antonio Margarito or Yuri Foreman, assuming they win their upcoming fights.