Los Angeles Laker star Kobe Bryant (search) might have to kiss the prospect of becoming the next Michael Jordon goodbye thanks to sexual assault charges.

At a news conference Friday Bryant, who sat beside wife Vanessa, firmly denied engaging in a non-consensual act with the 19-year-old woman who brought the charge against him.

"I sit here in front of you guys, furious at myself, disgusted at myself for making the mistake of adultery," he said.

Bryant, 24, was charged Friday with a single count of felony sexual assault against the woman at an exclusive spa where he was staying when he came to Colorado for knee surgery. If convicted, he faces four years to life in prison or 20 years to life on probation, and a fine of up to $750,000.

Eagle County District Attorney Mark Hurlbert (search) filed the charge after spending two weeks reviewing evidence and consulting with other prosecutors, and said he "can prove this case beyond a reasonable doubt."

"Given the seriousness of the crime, and given the type of crime, it's something the prosecutor does not get into lightly," Hurlbert said Saturday on NBC's Weekend Today show.

Bryant's attorney, Pamela Mackey, said he will plead innocent.

Even if he is ultimately cleared, the criminal charge and admission of infidelity will almost certainly change the public perception of Bryant.

His squeaky-clean image made him one of the NBA's most recognizable and marketable stars. He recently signed a multimillion-dollar deal with Nike and has endorsement deals with Sprite, McDonald's, and Spalding.

A poll last fall by Burns Sports & Celebrities Inc. rated him the third-best product endorser in sports, behind Tiger Woods and Michael Jordan.

Bryant could lose millions of dollars in endorsements.

"The image was of a perfect role model, a superstar athlete who didn't have a parking ticket, the all-American boy and now, well, that image is tarnished," said Bob Williams, chief executive of Burns Sports. "As of today and until the trial, his image is going to take a beating."

Nike spokesman Nigel Powell said Friday, "Kobe has stated that he is innocent of the charges today. You will understand that this is a legal matter and we cannot comment further at this time."

Bryant's team could feel the sting as well.

The case is bound to take an emotional toll on Bryant, and a conviction would mean the Lakers would lose one of the league's best players in the prime of his career.

"Naturally, we're disappointed with today's announcement," Lakers general manager Mitch Kupchak said. "While there are many questions concerning this issue, we will wait for time and the judicial process to answer them."

Bryant said Friday he was thinking more of his family than his career.

"I have a lot at stake, and it has nothing to do with the game of basketball and it has nothing to do with endorsements," said Bryant, who fought back tears several times during the news conference.

"It has to do with my family and being falsely accused. And, I'm innocent. We're going to fight this all the way to the end."

Mackey criticized the decision to file charges, saying the evidence wasn't strong enough to prove the allegations beyond reasonable doubt.

"The evidence in this case falls far, far short of that standing. The accusations in this case cannot be proven because they are false," she said.

Legal experts said that prosecutors have a tough task because the case appears to hinge mainly on Bryant's word against that of the alleged victim.

"He said, she said" cases can be the toughest for prosecutors, said Steve Kron, a longtime sports criminal defense attorney in Los Angeles.

"How do they prove it's not consensual? It's hard to prove (with) two adults in a room having sex that the sex was not consensual.

"Do you have witnesses or physical evidence? Was she bruised, scratched, injured in some fashion?"

The alleged assault occurred June 30 at the gated Lodge & Spa at Cordillera (search) in nearby Edwards, where the woman worked at the front desk.

Bryant returned to California after undergoing unspecified medical tests in Colorado on July 2 at the request of investigators. He returned to Eagle on July 4, surrendered to authorities and was released an hour later after posting $25,000 bond.

Bryant is scheduled to return to Eagle for a hearing on Aug. 6.

Bryant tearfully addressed his wife at the news conference.

"You're a blessing, you're a piece of my heart, the air I breathe, and you're the strongest person I know and I'm so sorry for having to put you through this, putting my family through this," Bryant said, pausing several times as he spoke.

Vanessa Bryant, who gave birth to the couple's first child in January, did not speak at the news conference. In a statement released earlier, she said her husband was not a criminal.

"He is a loving and kind husband and father," she said. "I believe in his innocence. Because I know him to be innocent, I will stand by him and we will face this together."

The Associated Press contributed to this report.