Strikeforce welterweight champion Nick Diaz and former IBF super-middleweight champion Jeff Lacy have agreements in place to box this fall, representatives for both fighters confirmed Friday.

According to a release issued by promoter Don Chargin, Lacy officially signed on to the bout Friday morning. Diaz's manager, Cesar Gracie, told ESPN.com that the 27-year-old mixed martial artist is "tentatively" set to fight Lacy and has signed papers to that effect.

Unless Zuffa offers UFC welterweight champion Georges St. Pierre a fight during same time period, Diaz, who ESPN.com currently ranks as the No. 3 welterweight in MMA, will challenge Lacy.

"Nick's [MMA] contract takes precedence," Gracie said. "That's why we're not out there telling everyone what we're going to do. We're trying to work together with the UFC and not against them. And we're trying to do things the right way."

"As far as I'm concerned he's locked into boxing, but Nick has been very cooperative," Chargin said. "We're not going to get into a contest where we're trying to hold him and he's trying to get out. I think he'll be able to do both."

Gracie met with UFC executives on April 25 to discuss their options and came away feeling as if progress had been made.

Dave Sholler, UFC director of communications, told ESPN.com that no official response from the company will be made at this time. Strikeforce CEO Scott Coker did not respond to a request for comment.

Diaz's contract with Strikeforce includes a provision that allows him to fight in 2011. UFC president Dana White said last week that he intended to have face-to-face discussions with Diaz about his intentions. That meeting is yet to happen, said Gracie.

"So we have to move forward with what we're doing," Gracie said. "Of course, if those guys call and say they secured a date and it's going to conflict with boxing then it might change this whole thing up."

Diaz-Lacy, should it take place, would mark the first time an elite mixed martial arts champion attempted to fight an established boxer in his realm. In 2005, Diaz (25-7 in MMA) earned a unanimous decision victory his lone professional boxing appearance, a four-round bout in Sacrament, Calif. He is considered among the best pugilists in MMA.

Lacy, a resident of St. Petersburg, Fla., has fallen on hard times as a boxer. The 33-year-old former U.S. Olympian, unbeaten in 21 fights before losing a unanimous decision to Joe Calzaghe in 2006, dropped three of his last four bouts, including an embarrassing decision to journeyman Dhafir Smith in December. Lacy (25-4) also lost on points to Jermain Taylor and Roy Jones Jr.

Last month, amid speculation that Diaz could fight Fernando Vargas or even current middleweight champion Sergio Martinez, Lacy said of the mixed martial artist: "For the right price, I'm more than interested in heading to his turf and put my fist in his mouth and silencing him."

"I expected more resistance from fight fans and media in regards to this matchup but it's amazing as to the hundreds of calls and emails I've received from fans on both sides wanting to see this matchup take place," Chagrin, a Hall of Fame boxing promoter, said in a statement. "I've received more than a few inquiries from some other very high-profile boxers that want to step up and fight Nick. It's been a real whirlwind.

"I believe that if Nick had been one of those kids who had picked up boxing from a youth, he'd undoubtedly be a world-champion today. Sometime within the next two weeks I'll be personally making the trek to Cesar Gracie's gym to setup a private, closed door sparring session between Nick and a few nameless top-level contenders I have in mind."

The fight, titled "Breaking History," includes an agreed-upon venue and a date, Gracie said, though neither have been announced. Chargin said he expects to have a venue and location finalized within 30 days. The promoter declined to discuss purse splits for either fighter.

Showtime, which broadcasts Diaz's Strikeforce fights, declined to speak about its interest in carrying Diaz-Lacy. Diaz's MMA bouts are not contractually bound to air on Showtime. Gracie previously said HBO is not an option for the fight. Chargin, referencing Diaz's popularity and the success of the UFC, also said pay-per-view is an option.

Josh Gross covers mixed martial arts for ESPN.com.