Boxing great Oscar De La Hoya has checked into a rehabilitation clinic in California.

De La Hoya went into rehab within the last few weeks, TMZ first reported Saturday. The nature of his problem is not known.

"He is my friend and I wish him well," Golden Boy CEO Richard Schaefer, De La Hoya's close friend, told ESPN.com at the Bell Centre in Montreal on Saturday night, where he was promoting the Jean Pascal-Bernard Hopkins light heavyweight championship rematch. "I'm sure that all the fans are joining me in wishing him the best."

Schaefer said De La Hoya was still in rehab, which is why he is not at one of his company's biggest fights of the year.

"After doing an honest evaluation of myself, I recognize that there are certain issues that I need to work on," De La Hoya said in a statement. "Like everyone, I have my flaws, and I do not want to be one of those people that is afraid to admit and address those flaws.

"Throughout my career and my life, I have always met all challenges head-on, and this is no different. I am confident that with the support of my family and friends, I will become a stronger, healthier person."

De La Hoya asked for privacy as he goes through the process.

De La Hoya, a former six-division titleholder, had a career record of 39-6. He retired shortly after losing by technical knockout to Manny Pacquiao in December 2008.