LAS VEGAS -- Floyd Mayweather Jr. weighed in at 146 pounds on Friday afternoon, two pounds heavier than the weight stipulated in the contract for his comeback fight against lightweight champion Juan Manuel Marquez on Saturday night at the MGM Grand Garden Arena.

The excess weight will cost Mayweather $300,000 per pound, meaning Marquez will get an additional $600,000 on top of his $3.2 million guarantee, a source told ESPN.com. Mayweather's minimum guarantee is $10 million, a figure likely to dramatically increase after the pay-per-view receipts are counted.

Marquez, who has never fought heavier than 135 pounds, comfortably made 142 pounds, two less than the 144-pound contract weight.

At Mayweather's request, nobody would speak publicly about the contract weight throughout the promotion that kicked off in early May and continued into the fall when the fight was postponed from July 18 because of a Mayweather rib injury.

However, several sources with direct knowledge of the contract told ESPN.com all along that the contract maximum weight was 144 pounds, three less than the 147-pound welterweight maximum.

But after Friday's weigh-in, Golden Boy CEO Richard Schaefer finally addressed the issue, telling ESPN.com, "The fight was contracted as a welterweight fight with an agreed upon weight of 144 pounds. However, there were pre-negotiated weight penalties built in."

Schaefer would not disclose the dollar figure, but another source with direct knowledge of the contract told ESPN.com that the penalty was $300,000 per pound if either fighter was overweight.

According to the source, the Marquez camp knew Wednesday night that Mayweather would not make weight because Mayweather's team made overtures to Golden Boy Promotions in an effort to have Marquez agree to change weight on the bout agreements to be filed with the Nevada State Athletic Commission.

However, Marquez's contract had already been filed reading 144 pounds, according to commission executive director Keith Kizer. But Kizer said the bout agreement was retrieved from the commission by Golden Boy Promotions and changed to 147 with Marquez initialing it.

Mayweather's contract with 147 pounds was not filed with the commission until minutes before the weigh-in. Kizer said it was supposed to be filed on Wednesday.

Kizer said the Mayweather camp asked to file it Thursday and he said OK, but that deadline also came and went.

"We were very unhappy with the lateness of Mr. Mayweather's contract," Kizer said.

Kizer said that had the bout agreements not been changed to 147, Mayweather would have faced a fine from the commission in addition to whatever penalty he had agreed to pay Marquez. For being two pounds overweight, Kizer said the penalty would have been 10 percent of his purse, or $1 million. Had he been three pounds over (147 pounds), the figure would have jumped to a 20 percent fine.

Dan Rafael is ESPN.com's boxing writer.