Groups were in mediation for 9 hours

After nine hours in mediation on Tuesday, the camps of Manny Pacquiao and Floyd Mayweather Jr. did not reach a resolution in their effort to overcome their differences in finalizing a super fight between the top two pound-for-pound fighters in the world.

If a deal is reached, the welterweight title bout is supposed to take place March 13 at the MGM Grand in Las Vegas.

Top Rank's Bob Arum and Todd duBoef, along with their legal team, Golden Boy's Richard Schaefer, Oscar De La Hoya, their legal team, and Mayweather manager Al Haymon spent the day with mediator Daniel Weinstein at offices in Santa Monica, Calif., hoping to pave the way for potentially the richest fight in boxing history.

On Monday, Arum said the fighters were supposed to have been available by telephone.

After beginning the process at 9:30 a.m. PT and leaving at approximately 6:30 p.m. PT, no deal had been reached.

"Mediation is still ongoing," one of Top Rank's lawyers told ESPN Deportes' Jaime Mota.

Weinstein has placed a gag order on all parties.

It is unclear if the talks will resume on Wednesday.

When reached on his cell phone, Arum said he had no comment because of the mediator's gag order. DuBoef said the same thing in an e-mail to ESPN.com. Schaefer did not respond to a message.

Weinstein, a retired federal judge, knows the parties well. He mediated a June 2007 settlement when Top Rank and Golden Boy were embroiled in a series of lawsuits, including a brutal battle over ownership of the promotional rights to Pacquiao, who had signed contracts with both companies before eventually pledging his loyalty to Top Rank.

Under that agreement, the various lawsuits were dropped and Top Rank retained Pacquiao's promotional rights, with Golden Boy receiving a percentage of Top Rank's profits from his bouts.

The agreement worked well for the past two years as the companies co-promoted several major bouts, including Pacquiao-Ricky Hatton, Pacquiao-Juan Manuel Marquez II, Pacquiao-Marco Antonio Barrera II, Bernard Hopkins-Kelly Pavlik and Miguel Cotto-Shane Mosley.

But the bad blood boiled again during the final stages of negotiations for Pacquiao-Mayweather.

They had agreed to everything in the deal except for the method of drug testing for the boxers.

Although the Nevada State Athletic Commission, which would oversee the bout, requires only urine testing, Mayweather has insisted on random blood testing. Both sides have already agreed to unlimited random urine testing.

Pacquiao (50-3-2, 38 KOs), who didn't want any blood testing, agreed to take three blood tests: one during the week of the kickoff news conference, which would take place next week if they can make a deal, one random test to be conducted no later than 30 days before the fight and a final test in his dressing room after the fight. Mayweather (40-0, 25 KOs) would be subject to the same testing procedures.

Besides Weinstein trying to mediate a resolution to the drug testing issue, there is also the matter of the defamation lawsuit Pacquiao filed last week in Nevada U.S. District Court against Mayweather Jr., Schaefer, De La Hoya, Floyd Mayweather Sr., Roger Mayweather and Mayweather Promotions.

Pacquiao alleges that they made false and defamatory statements and sullied his reputation by accusing him of taking performance-enhancing drugs. Pacquiao denies he has ever used PEDs and has never failed a drug test.

At issue is also Golden Boy's continued involvement in Pacquaio's contract. With Golden Boy representing Mayweather and allegedly accusing Pacquiao of using performance enhancing drugs, Arum believes it has diminished Pacquiao and that Golden Boy should no longer be entitled to share in the money his bouts generate, especially when it also is making money off Mayweather.

If the mediation fails, Arum has repeatedly said he will match Pacquiao with junior middleweight titlist Yuri Foreman, whom he also promotes, on March 20 at the Thomas & Mack Center in Las Vegas so Pacquiao could attempt to win a title in a record-extending eighth weight division.

Mayweather could still fight on March 13 at the MGM Grand and potentially face former junior welterweight titlist Paulie Malignaggi.

Dan Rafael covers boxing for ESPN.com.