The closing act in Fernando Vargas' boxing career has been put on hold.

Vargas' Sept. 8 bout with Ricardo Mayorga, a fight at Staples Center that the Oxnard fighter has said will be the last of his career, has been postponed because Vargas is suffering from anemia.

"I had no choice," said Vargas, clearly downcast but also relieved to learn why he had been feeling ill and weak during recent training efforts. " I can't fight in this condition.

"I feel bad, but I'm thankful to God that we found this right now, because your life is on the line when you're in the ring. Maybe it's a blessing in disguise."

Upon discovery of the anemia, Vargas said his doctor recommended the fight be postponed telling him, "it would be detrimental to my health to fight in this condition. I said, You don't have to tell me twice.' "

Not only was he unwilling to risk his long-term health while fighting in a weakened condition — "I have kids, I want to be around" — but his desire was to go out with one last fight to show what he could do, and the condition was not going to allow that.

"Absolutely," he said. "This was to show one last thing. But nothing is more important than your health."

Vargas said doctors have told him he could resume light physical activity, such as jogging, in little more than a week, but it could be three weeks before he would be sufficiently recovered to resume full training. That necessitated the postponement; no new date has been determined.

"Hopefully we can get it done soon," said Joe Pecora, Vargas' business manager and vice president of his promotional firm, Vargas Entertainment Promotions, which is one of the promoters of the Staples Center event.

"This was devastating for this kid. He wanted Mayorga bad, and he'll get him. But we want to make sure he's at 100 percent when he does get him."

Pecora said the Mayorga camp had been informed of the news, but he had not yet heard any reaction.

The anemia — a deficiency of red blood cells, reducing the ability of the blood to move oxygen throughout the body — was discovered when Vargas visited a doctor this week after feeling too ill to train on Wednesday afternoon, something the boxer knew was highly unusual.

"I thought I had the stomach flu, which is strange for me," he said. "I've only got sick one time in 11 years I can remember. Thursday morning, I felt worse."

And so Vargas visited his doctor in Camarillo, telling him he felt sick to his stomach and weak. Tests uncovered the anemia; further examination by a specialist, and a Saturday morning gastric endoscopy — a procedure in which a small camera is inserted into the stomach — found sores on the surfaces of Vargas' stomach. Vargas said indications were the anemia had been caused by bleeding ulcers — "I had been bleeding, but I'm not any more" — and those ulcers, in turn, may have been caused by Vargas' overuse of aspirin during training.

"Every athlete has aches and pains," said Vargas, "and I guess I was taking a little bit more aspirin than recommended. (The doctor) said it's very common for people who take a lot of aspirin to have this."

Clearly concerned some fans might think he was looking for a way to put off the fight, Vargas stressed the nature of the medical findings.

"This is blood work," he said. "Blood work don't lie. People are not going to put their professional licenses on the line to say this. There's way easier excuses, like hurting my hand, like other fighters have done."

Rescheduling the fight at its current venue could be a challenge given the crowded Staples Center calendar. A preliminary look at the Web site of the arena and its three primary tenants — the Kings, Lakers and Clippers — shows just five open Saturdays the rest of 2007: Sept. 15 and 29, Oct. 13, and Dec. 22 and 29.