Manny Pacquiao fights Juan Manuel Marquez in November © Getty Images Enlarge

The much-anticipated super-fight between Manny Pacquiao and Floyd Mayweather Jnr has taken a significant step closer after Pacquiao's promoter, Bob Arum, said his charge is willing to agree to random drug testing - but not by the United States Anti-Doping Agency (USADA).

Negotiations have previously collapsed over the timing of sampling, with Pacquiao refusing to accept Mayweather's demands of Olympic-style probes right up until fight night.

But while Arum's revelation does fuel hopes of a bout materialising, the situation is clouded by Pacquiao's decision to file a defamation lawsuit against Mayweather, which has done nothing to quell the animosity between the camps.

"We have agreed in the Pacquiao camp to unlimited random testing done by a responsible, neutral organization," Arum told Yahoo. "We don't believe USADA is a neutral organization.

"I don't think anybody's test is as vigorous as the test administered by the Olympic Organization. And we can arrange for the Olympic Organization to handle the test under the supervision of the Athletic commission respective of the state where the fight is going to be held.

"We're not going to make this into a cowboy situation. We have an organization that has no authority [USADA] and even does it [blood testing] without reporting to an organization that is responsible for the conduct of the fight.

"We are focusing on Pacquiao v Marquez fight [on November 12]. And if Pacquiao beats Marquez again and then if Mayweather says he's agreeable to us, then we can have the Mayweather vs Pacquiao fight next year."

© ESPN Sports Media Ltd.