US boxer Floyd Mayweather was released from a Las Vegas prison early Friday after serving two months of a three-month sentence for domestic battery, police said.
"I can confirm that he was released this morning at about 12:30 am," Las Vegas police spokeswoman Laura Meltzer told AFP.
Photographs published in local media showed one of the boxer's daughters and rapper 50 Cent waiting for him at the exit. The boxer made no comment to reporters.
Mayweather, 35, was sentenced to 90 days in jail after pleading guilty to striking his former girlfriend as their children watched in September 2010. He began serving his sentence at the Clark County Detention Center on June 1.
Police gave no official reason for his early release, but according to The Los Angeles Times, prison overcrowding and good behaviour may have led authorities to reduce his sentence.
After a delay so he could fight Puerto Rican star Miguel Cotto in May, a bout which he won by unanimous decision, the unbeaten Mayweather began his sentence, with three days taken off for time served.
Police kept Mayweather apart from the general prison population, saying they wanted to protect him from other inmates, but that kept him confined to his cell 23 hours a day.
In June, a judge denied an emergency motion seeking to allow Mayweather to complete his sentence under house arrest.
According to Forbes magazine, Mayweather was the highest-paid athlete in the world in 2011, with revenues of $US85 million ($A81.6 million).
But Mayweather -- whose record stands at 43-0 -- has yet to fight Filipino icon Manny Pacquiao in the bout most boxing fans have sought for several years while both men are at the peak of their skills.