Golden Boy Promotions CEO  Richard Schaefer confirmed an earlier report by RingTV.com that Robert Guerrero injured his left shoulder and pulled out of his junior welterweight debut against Marcos Maidana on Aug. 27, which was to be televised on HBO.

Guerrero and Maidana were to fight for what the WBA calls its "regular" junior welterweight title, which would've been Guerrero's debut at 140 pounds.

"Basically, I was informed this morning about an hour ago or an hour and 15 minutes ago, at 9 a.m. Los Angeles time, that Robert Guerrero injured his left shoulder last night sparring and that he couldn't move his arm last night," said Schaefer, who later formally announced the news during a national conference call.

"They iced it, and they were hoping that it was going to get better, but it didn't. As a matter of fact, it got worse to the point where he can't even put on a shirt or a jacket. They had to break training camp in Big Bear, Calif., and they are currently on their way down the hill from Big Bear to Ontario (Calif.)."

Schaefer said that the 28-year-old Guerrero (29-1-1, 18 knockouts) is on his way to San Jose to be examined by a doctor and, perhaps on Monday, by San Franciso 49ers team physician Michael Dillingham.

"They will be flying out to San Jose in a little while, and they are scheduled to do an MRI in Redwood City, and he's going to be under the care of  Dr. Dillingham, who is the team physician for the San Franciso 49ers who has treated players like Joe Montana and Barry Bonds and Steve Young for shoulder injuries," said Schaefer.

"As a matter of fact, the MRI is going to be taken at that facility at 2:30 or so today [Thursday], and Dr. Dillingham, however, is only going to be back on Monday. But we are going to get the first read on the MRI from Dr. Dillingham's team, and I anticipate that this afternoon sometime."

Schaefer said that he has informed HBO that the entire card has to be canceled.

"I have spoken to HBO and I have informed them of the situation. We also have also informed the other participants on the card, including Marcos Maidana. They are devastated," said Schaefer. "It was a fight that we were all looking forward to, the fight fans, the networks and everybody.

"It was one of those great match ups, but HBO is obviously interested in rescheduling the fight once we know a little bit more on what kind of injury it is."

Guerrero-Maidana was to take place at the H.P. Pavillion in San Jose, Calif., not far from Guerrero's hometown of Gilroy.

"We were going to have a sellout in San Jose," said Schaefer. "It was a much talked about fight in the Bay Area, and fight fans were coming in the thousands and thousands, and they, of course, are going to get a full refund for their purchases."

The injury is the latest setback in what has been an inspirational but sometimes-difficult career for the 28-year-old Guerrero (29-1-1, 18 knockouts), who is coming off of a one-sided, unanimous decision victory over Australia's hard-punching Michael Katsidis (28-4, 23 KOs) in April.

Guerrero chose in March of last year to pull out of a scheduled clash with Katsidis in order to be with wife Casey during her recovery from a bone marrow transplant. Guerrero's often had to drive 50 or so miles back and forth from the hospital to their home in Gilroy, Calif., to care for their two young children, Robert Jr., 4, and, Savannah, 6.

Guerrero's devotion to his wife and family were recognized when he received The Bill Crawford Award for Courage In The Face of Adversity from the Boxing Writers Association of America.

Assured that Casey's cancer was in remission, Guerrero returned to the ring with an eighth-round knockout of Roberto David Arrieta in April of last year.

Guerrero was after his 14th consecutive victory against Maidana (30-2, 27 KOs). He last suffered defeat by a split-decision to Gamaliel Diaz in December 2005 but won their rematch with a sixth-round knockout in June 2006.

A two-time IBF featherweight and one-time IBF super featherweight beltholder, Guerrero's comeback has included unanimous decisions over former four-time titleholder and Cuban Olympic gold medalist Joel Casamayor (38-5-1, 22 KOs) in July and a Vicente Escobedo (23-3, 14 KOs) in November.

Guerrero overcame a re-injured left hand to defeat Escobedo.

Lem Satterfield can be reached at [email protected]