It's all but set. From the AP:
Manny Pacquiao likely will fight Floyd Mayweather Jr. on March 13 after agreeing to a proposal from promoter Bob Arum on Friday.
Arum presented "what he thought was the best proposal he can bring" during a two-hour breakfast meeting with Pacquiao in Manila, said Michael Koncz, an adviser of the Philippine boxing idol.
"Manny has some additional requirements, requests, which Arum didn't think was a problem," Koncz said. "The requests of Manny were so realistic that Arum doesn't feel it's a problem and it's pretty much a done deal."
...
"We all believe that it will be done," Koncz said.
In an interview with GMA television, Pacquiao said, "March 13 is OK."
One step closer to the biggest, most important fight in at least 20 years being made.
If this fight has gotten made this quickly, isn't that amazing? It speaks on some levels to the amount of money at stake here that Mayweather and Pacquiao could come to terms so quickly, but before this fight was even a possibility (or anything else quite this big), both Floyd and Manny and their teams had dragged out negotiations to the point of getting ridiculous in the past.
Pacquiao would likely take a seven-week training camp, according to Koncz, but then Koncz has said lots of things in the past, so don't bet your house on it or anything. Freddie Roach will probably want at least eight weeks.
This fight is pretty much put up or shut up on both parties. Someone will win, someone will lose, and the winner is The Man in professional boxing. In a lot of ways, it's like we had a decade of boxing, and just after that decade ends, the two top fighters meet to figure out who the Fighter of the Decade really was.
Both in shape, both in their primes, both about to make a ton of money.