Mayweather, who grew up in Grand Rapids, Mich., said he began training for the Guerrero fight Wednesday by running in the gym of Ottawa Hills High School in his hometown.
"This is a guy I know I can't overlook," Mayweather said of Guerrero (31-1-1, 18 KOs), the WBC's interim welterweight champion.
Manny Pacquiao had been Mayweather's only rival in recent years, though he had a pair of losses in 2012. Asked Thursday about a possible future fight with the Filipino, Mayweather pointed to the "crucial knockout" he suffered at the hands of Juan Manuel Marquez in December.
"If people don't know, Floyd Mayweather's not scared of (any) opponent," Mayweather said. "You just don't wake up overnight and just become (the best) pound-for-pound (fighter). And sometimes people talk about my legacy. If my legacy was based upon just one fight, then I didn't need to fight 43 fights."
Shifting to his upcoming fight, Mayweather promised an entertaining bout with Guerrero.
"Call your local cable company, because it's Showtime, baby," he said.