Floyd Mayweather Jr. will fight Robert Guerrero on May 4, and he’s changing television networks to do it.

The biggest star in boxing dropped a surprise today while announcing his long-rumored next bout: After several years on HBO, Mayweather is moving to Showtime with a lucrative multi-fight deal.

Mayweather’s move is a coup for Showtime, the CBS-owned network that has always trailed behind HBO in boxing prominence. Mayweather (43-0, 26 KOs) is the sport’s biggest moneymaker, and his new revenue-sharing deal with Showtime could include up to six fights over 30 months.

“They were extremely aggressive from the start, and they made it clear they want Floyd Mayweather to be the face of Showtime,” Mayweather adviser Leonard Ellerbe told The Associated Press. “It’s the ultimate compliment to a fighter like Floyd. They were aggressive, and the deal that they put on the table was essentially a deal that you can’t refuse.”

Mayweather’s first bout is against Guerrero (31-1-1, 18 KOs), the WBC’s interim welterweight champion. The fight likely will be at the MGM Grand Garden in Las Vegas.

Mayweather turns 36 on Sunday, but the unbeaten WBC 147-pound champion has shown no signs of age in the ring. He hasn’t fought since beating Miguel Cotto last May 5, and he spent two months in jail last summer after his conviction in a misdemeanor domestic battery case.

“He has a renewed motivation to stay active and to take on everybody out there,” Ellerbe said. “When Floyd is more active, he’s going to be beyond untouchable. He’s proved he can stay sharp with those layoffs in the past, but he’s going to be more active now.”

Guerrero beat out several contenders to get the biggest payday of his career and a long-awaited shot at his sport’s biggest name. Guerrero, from Gilroy, Calif., is a onetime featherweight champion who hasn’t lost since 2005, beating welterweight Andre Berto in a thrilling fight last November.

“On May 4th I’m going to shock the world,” Guerrero tweeted.

Ellerbe said Mayweather chose Guerrero as his next opponent because of his toughness and crowd-pleasing style.

“He definitely earned the right to fight Floyd,” Ellerbe said. “He won the Mayweather sweepstakes, so now he gets to see what the grand prize is, and when he opens up that grand prize, it’s going to be a can of (tail) whooping.”

Mayweather has been on HBO for essentially his entire professional career, which began after the 1996 Atlanta Olympics. HBO has been the home for nearly all of boxing’s biggest stars and biggest fights over the past three decades.

The pay-cable network has an extensive array of boxing-related programming along with hundreds of fights on its regular network and pay-per-view arm. Mayweather starred in HBO’s popular “24/7” reality series before each of his last six bouts, further growing his celebrity with the four-episode showcases of his Vegas lifestyle and irrepressible personality.

“We made an aggressive and responsible pay-per-view offer,” HBO said in a statement from spokesman Kevin Flaherty. “Now we move on. We are focused on the best boxing franchise in the television business. We are proud of the roster of superstar fighters and emerging stars who are scheduled to appear on the multiple HBO television platforms this year.”

Manny Pacquiao was Mayweather’s only rival for boxing supremacy in recent years before the Filipino congressman’s back-to-back losses last year. Top Rank promoter Bob Arum moved Pacquiao off HBO for one fight in 2011, beating Sugar Shane Mosley on Showtime, but returned to HBO for Pacquiao’s next bout.

Mayweather usually partners with Golden Boy Promotions to organize his fights, but the boxer essentially serves as his own promoter and cuts his own financial deals with help from adviser Al Haymon.

“All the fighters and promoters out there should be applauding Floyd,” Ellerbe said. “He’s elevating the sport and bringing more eyeballs to it. More importantly, he’s changing the pay structure in the sport. He’s setting that bar higher for everybody.”

Mayweather is making another big change for his next fight: He has hired his father, Floyd Sr., as his trainer. The younger Mayweather was estranged from his father for long stretches of the past several years while he trained under his uncle, Roger.

Golden Boy is working on a deal to put Mexican star Saul “Canelo” Alvarez on the undercard of Mayweather’s bout with Guerrero, possibly against Austin Trout. Alvarez, the WBC 154-pound champion, could be Mayweather’s next opponent in September.