It's always a bit surprising when fellow athletes defend cheaters in their midst, something Serena Williams seemed more than eager to do for Maria Sharapova.

Then again, perhaps Williams can afford to be a bit magnanimous since Sharapova's doping never really affected her. She owned their head-to-head series, winning the last 18 meetings over more than a decade.

''I think most people were happy she was upfront and very honest and showed a lot of courage to admit to what she had done and what she had neglected to look at in terms of the list at the end of the year,'' Williams said.

Well, maybe not all people. Nike and other sponsors wasted no time in dumping Sharapova after she announced this week she tested positive for meldonium at the Australian Open in January.

They stuck their fingers in the air to see which way the wind was blowing. They considered what the fallout would be among tennis fans who bought into the Sharapova image machine, only to find out that image wasn't everything they thought it was.

Then they decided that the honesty and courage Williams spoke of came way too late.

Sharapova might get a pass from some for not reading the emails that warned her that the drug manufactured in Latvia was added to the banned list this year by the World Anti-Doping Agency because it aids oxygen uptake and endurance.

But the fact she acknowledged taking it for the last 10 years throws into question the very legitimacy of a career that has made Sharapova very rich.

Yes, she may have won her 35 singles titles - five of them in Grand Slam events - even without the drug. She may not have needed meldonium to become such a star that Forbes estimated her endorsement income at $23 million for last year alone.

She might have found some way to dig down deep in the final games of a match when exhausted without having to use a drug that helps her keep playing.

But how are we to know what was real and what was aided? How will the players she beat along the way ever know if they were beaten fair and square?

The simple answer is we don't, and they won't. And that more than anything will always cloud the career of the Russian who parlayed her game and her looks into stardom that transcended the insular world of tennis.

That's the legacy Sharapova will have to deal with, perhaps sooner than later. She faces a lengthy ban from the International Tennis Federation that will likely end her year and could end her career.

She acknowledged as much Monday in a press conference in Los Angeles, where she was about as candid and open about what happened as any athlete ever busted for performance enhancing drugs has been.

''I know that with this, I face consequences,'' Sharapova. ''I don't want to end my career this way, and I really hope I will be given another chance to play this game.''

That was good enough for Williams, though others weren't as forgiving. That included former teen-age prodigy Jennifer Capriati, whose own career ended early because of injuries.

''I had to lose my career and never opted to cheat no matter what,'' Capriati wrote in a tweet. ''I had to throw in the towel and suffer.''

That might seem like sour grapes to some, but Capriati nailed it in another tweet where she said she wasn't lucky enough to have a high priced team of doctors to find a way for her ''to get around the system and wait for science to catch up.''

That such a big star was the first major casualty of drug testing in tennis isn't just bad for Sharapova and her endorsement income. It's bad for tennis, which constantly struggles to escape from its niche sport status.

Williams is the most dominant player in the history of the women's tennis, but she's 34 now and won't be around forever. Behind her are a bunch of names that only the most ardent readers of Tennis Magazine will recognize, so Sharapova's absence will be felt by the sport.

That doesn't mean Williams needs to defend her.

The fact is that Sharapova was using something to help her compete, and only held a press conference to admit it because she had no other choice. If anything, the people who run tennis were deferential to Sharapova by allowing her to try and control the message herself before they made an official announcement.

No matter what Williams might think, there's nothing courageous about that.

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Tim Dahlberg is a national sports columnist for The Associated Press. Write to him at tdahlberg(at)ap.org or http://twitter.com/timdahlberg