Representatives for Oscar De La Hoya and Manny Pacquiao met Wednesday in Los Angeles to begin hammering out a deal for a Dec. 6 non-title welterweight bout at the MGM Grand in Las Vegas.
Richard Schaefer, chief executive for Golden Boy Promotions, which represents De La Hoya, and Bob Arum, president of Top Rank, which represents Pacquiao, met for two hours but are still days away from a deal, Schaefer said.
"I would say, cautiously optimistic, there's maybe a 75% chance that the fight will happen," said Schaefer, who will meet with De La Hoya next week.
De La Hoya, 35, one of boxing's most popular fighters, has said he would fight once more before retiring.
Among the issues being discussed about a De La Hoya-Pacquiao bout is the weight limit, which is expected to be 147 pounds but could go as high as 150, Schaefer said.
Both boxers would need to make considerable weight changes to make the fight.
De La Hoya (39-5, 30 knockouts) weighed in at 150 pounds for his last fight against Steve Forbes, the lightest he has been since taking on Arturo Gatti at 147 pounds in March 2001.
De La Hoya is 2-2 in the welterweight division, losing to Felix Trinidad and Shane Mosley, and defeating Gatti and Derrell Coley.
"You can actually lose a fight on the scales," Schaefer said. "To make 147 would be a big concession on Oscar's part."
Pacquiao, 29, began his professional career as a 106-pound straw-weight. He began fighting at 130 pounds in 2005. In his last fight, he moved up to the 135-pound lightweight division for the first time, taking the World Boxing Council title from David Diaz with a ninth-round knockout in Las Vegas.
Although welterweight would be a big jump for Pacquiao, his trainer, Freddie Roach, has said Pacquiao entered the ring against Diaz weighing 146 pounds.
Pacquiao is the first Asian to win boxing titles in four different weight classes.
The size of the gloves has been another sticking point in negotiations. Pacquiao (47-3-2, 35 KOs) is accustomed to fighting with eight-ounce gloves, but the Nevada Athletic Commission requires fighters to use 10-ounce gloves for any bout at 147 pounds or higher.
Schaefer said Pacquiao was also looking for a substantial split of the revenue.
Pacquiao built his career with impressive bouts against the top Mexican fighters, defeating Marco Antonio Barrera, Erik Morales and Juan Manuel Marquez.
De La Hoya has fought as high as the 160-pound middleweight division. He first gained notice as a 1992 Olympic gold medalist at 132 pounds.
Shane Mosley teased Ricardo Mayorga about his lack of conditioning during a news conference Thursday to promote their Sept. 27 middleweight bout at the Home Depot Center. Mayorga (28-6-1, 23 KOs) responded by lighting up a cigarette.
The fighters exchanged light-hearted barbs at the Millennium Biltmore Hotel in Los Angeles, but Mosley (44-5, 37 KOs) turned serious when asked about the importance of his first fight in Southern California in nearly eight years.
"It feels good to be back in L.A.," said Mosley, a former four-time world champion. "They can see me live, in person, and I truly am the fighter everybody says I am."