Shane Mosley, 43, comes out of retirement to fight Ricardo Mayorga

Former pound-for-pound king "Sugar" Shane Mosley, a former three-division world champion who was involved in a string of major fights, is coming out of retirement at age 43 for a grudge match with 41-year-old Ricardo Mayorga.

Mosley announced that his company, Sugar Shane Mosley Promotions, will promote a card on which he will fight the former welterweight and junior middleweight titlist in a rematch on Aug. 29 on pay-per-view at a location to be announced in Southern California.

The junior middleweight fight materialized, Mosley said, because the two have been going back and forth with each other in a war of words on Twitter for months, mainly with Mayorga antagonizing Mosley.

"Mayorga was talking s---, and I ran into him in Vegas. Things escalated and, boom, rematch," Mosley said.

Mosley, who won world titles at lightweight, welterweight and junior middleweight, and Mayorga met in 2008 in Carson, California, and Mosley knocked him out with one second left in the 12th and final round of what had been a competitive fight.

In the fight following his victory against Mayorga, Mosley (47-9-1, 39 KOs) pulled off a huge upset, knocking out Antonio Margarito in the ninth round to win a welterweight world title for the second time.

But then came the downward spiral. Mosley lost his next fight by lopsided decision to Floyd Mayweather to start a 1-4-1 streak (that included a similarly one-sided decision loss to Manny Pacquiao) before he retired following a seventh-round stoppage loss in Australia to Anthony Mundine in November 2013.

But Mosley has remained close to boxing since retiring. He has continued to stay in shape and go the gym regularly, where he trains his 24-year-old son, middleweight Shane Mosley Jr. (4-1, 4 KOs), whom Mosley said would fight on his undercard.

"I'm planning to show the world what (22 months) off did for me. They think I'm finished? I'm far from finished," Mosley told ESPN.com. "I am in the best shape of my life. I feel bad for Mayorga. No one knows how good I really am. I am going to kill him."

The Twitter battle between Mosley and Mayorga, one of boxing's most notorious trash talkers, has been quite amusing in recent months, including Mayorga's boast that he would make Mosley wash his dishes.

"He's been mouthing off on Twitter for months now," Mosley said. "He needs to be shut up. If there's anybody that needs his ass kicked, it's him. The time for hiding his ass on social media is over. I'm ready to beat him just like I did last time. Mayorga is a beer-swilling, butt-smoking a--h--- and I'll fight him as soon as he can stumble into the ring. I'll beat him down again.

"I'm gonna give him a beating for his Tweeting."

Both fighters also predicted knockouts on social media, Mosley in the sixth round and Mayorga calling for a second-round stoppage.

"I could do it in less but I want to give a real show," Mosley said. "All action all the time on this one. I plan to surprise a few people. I'm younger than (50-year-old) Bernard Hopkins and more deadly."

Mosley, the 1998 fighter of the year, said he originally planned to have the fight on Aug. 29 at the Staples Center in Los Angeles, but "(Al) Haymon found out and booked the venue from up under me. All good though. We got PPV locked in."

Haymon is putting on a Premier Boxing Champions card on ESPN on Aug. 29 at the Staples Center, which will be headlined by a much-anticipated featherweight fight between Los Angeles-based Mexicans Leo Santa Cruz and Abner Mares.

Mosley has faced a who's-who in boxing, including two career-defining wins against Oscar De La Hoya (although he later admitted to using undetectable designer steroids in the second fight), two wins against Fernando Vargas as well as wins against Margarito, Luis Collazo and eight lightweight title defenses all by knockout victory.

Mosley also suffered losses to some of boxing's biggest names -- Mayweather, Pacquiao, Winky Wright (twice), the late Vernon Forrest (twice), Miguel Cotto (in a very close fight) and a one-sided beating at the hands of Canelo Alvarez in 2012.

Mayorga (31-8-1, 25 KOs), of Nicaragua, won a welterweight belt in 2002 with a fifth-round knockout of the late Andrew "Six Heads" Lewis in a rematch but really made his name in 2003 when he knocked out Forrest in the third round to unify titles. Then he outpointed Forrest in an immediate rematch.

But then Mayorga lost a decision to Cory Spinks for the undisputed title later in 2003 and, although he eventually claimed a vacant junior middleweight belt, Mayorga never was back on top. Instead he became the perfect promotional foil against big names because of his outrageous verbal attack and lost to one star after another -- Felix Trinidad, De La Hoya, Mosley and Cotto. He did manage to defeat Vargas in 2007, sending him into retirement.

Since losing to Cotto in a junior middleweight title bout in 2011, Mayorga, who dabbled in MMA and had legal problems in his home country, has fought just twice, returning for a pair of knockout wins against sub-.500 opponents in 2014.