SAN JOSE, Calif. (AP) - A sixth world title and a possible big-money date with Floyd Mayweather Jr. pale in comparison to what's really on the line for Robert Guerrero each time he steps into the boxing ring.
After putting his career on hold to help his wife battle through leukemia, Guerrero is fighting for all those patients waiting for a donor like the one who saved Casey Guerrero's life two years ago.
A win on Saturday night in San Jose over Selcuk Aydin (23-0, 17 knockouts) would give Guerrero (29-1-1, 18 knockouts) the interim WBC welterweight title and a bigger platform to encourage people to sign up for bone marrow donor registries.
"That's a huge part of it, letting people know how they can help save people," Guerrero said. "As a professional athlete, I've been blessed to perform in front of millions of people around the world. It's my obligation to go out there and bring awareness and hope to this issue. I don't just fight for myself but I fight for the cause of saving people and bringing awareness to donors."
This issue has been at the forefront for Guerrero ever since his wife was first diagnosed with leukemia in October 2007, just days before Robert knocked out Martin Honorio in the first round before returning to Casey's side.
Guerrero soon balanced fighting, taking care of his childhood sweetheart and raising his 7-year-old daughter Savannah and 5-year-old son Robert Jr.
Some nights were spent on the hospital floor as Casey struggled with the disease, seeing her weight drop to under 100 pounds as chemo and cancer ravaged her once healthy body. Other days, he'd drive the hour back home to Gilroy to be with his kids, often breaking down in tears because of the overwhelming situation.
"I know it was difficult for him because he had to be the mom and the dad, taking care of the kids," Casey said recently in the backyard of the couple's home in Gilroy, the town just south of the Bay Area where the Guerreros grew up and first started dating at age 14.
"He had to learn how to brush my daughter's hair. He told me sometimes he would cry on the way home. It was difficult for him to deal with."
Casey had two relapses in the ensuing years and in 2009, doctors told her that the chemotherapy would not cure her and she needed a bone marrow transplant. Her brother and sister were not matches so she put her name on the registry.
She turned out to be a match with Katharina Zech, a 22-year-old from Munich, who got on a donor registry as soon as she turned 18 in honor of her grandfather, who had died from leukemia.
After three blood tests confirmed the compatibility, Zech underwent a process so simple yet so beneficial.
"It isn't painful at all. You can watch a movie during the time," said Zech, who is in town for this week's fight. "It's a blessing that I could do that."
Robert stayed by Casey's side during the recovery, withdrawing from a title bout against Michael Katsidis to focus on a more important fight: Casey's.
And now 18 months after surgery, Casey Guerrero looks and feels like her old self, although she acknowledges she gets tired a little easier.
"That's almost a different lifetime ago," said Casey's mother, Shelly O'Neal. "That was one of the hellish things that I've ever seen. I look back at pictures and wow, seeing her then and seeing her now."
Casey Guerrero and Zech had begun talking about a year after the transplant and got the chance for an emotional in-person meeting in April when Zech was in Arizona for a conference.
"It was like meeting my sister," Zech said.
That tearful moment is a highlight of an upcoming documentary about the Guerrero's journey through cancer and the fight world that they hope will inspire those who are sick, motivate others to sign up for donor registry lists and show what faith and family can overcome.
"It's an amazing story that touches a lot of people," Casey Guerrero said. "It's nice to be able to talk about and get it out there. A lot of people don't know how important or how easy being a donor is."
Guerrero has not fought since beating Katsidis in April 2011. He canceled his fight last summer against Marcos Maidana to undergo surgery on his left shoulder. He also has moved up two weight classes to take on Aydin, hoping it would lead to a date with Mayweather and the publicity that would surround a fight like that.
"That would be huge," Guerrero said. "Right now Floyd Mayweather is pound for pound the best fighter in boxing and also he's pound for pound one of the most recognized athletes in the world. To be able to go into the ring with him, all eyes would be on you. That's the opportunity to bring awareness to the cause. It would be a blessing."
The attention surrounding Guerrero and the talk of a possible date with Mayweather appear to have irritated Aydin, who mostly refused to participate in a pre-fight conference call but got on long enough to warn Guerrero to train harder and strengthen his jaw because Aydin was prepared to break it.
Guerrero took offense, saying he has always been a hard worker. He said he even found time to train while sleeping on the hospital floor to be near Casey and commuting home to take care of their children.
He said as Casey's health improved, so did his fighting because dealing with the tragedy made him a stronger person.
"He has no idea what I've been through," Guerrero said. "So he better be ready, that's all I got to say. For me to be talking like a politician and he's going to break my jaw, he better be ready because he talks a lot that he's going to break this and that. He better be ready because he don't know what I've been through in my life."