I often wonder if I compete on an even playing field

	Mariano Puerta's recent doping allegation is his second since 2003. He's also the fourth Argentine in four years to be implicated. Heinz Kluetmeier/SI
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Outspoken ATP tennis pro Justin Gimelstob is a frequent contributor to SI.com. Click here to read all of his columns.

The ongoing steroid controversy in baseball has everyone on edge about doping in sports. But sadly, tennis isn't immune to this issue -- far from it.

A few weeks ago, the French newspaper L'Equipe (the same publication that recently claimed Lance Armstrong tested positive for an illegal drug at the 1999 Tour de France) revealed that Mariano Puerta, a finalist at this year's French Open, tested positive for a banned substance during the tournament. So far, no other information has been revealed, as it is the ITF's and ATP's policy not to comment on any doping case until wrongdoing is confirmed.

But to be on the safe side, if you enjoy watching Puerta play, I would try and catch as much of him as possible during the last few tournaments this fall. The Argentine is no stranger to doping controversy: In February 2003, he tested positive for clenbuterol, an anti-asthma medication that is prohibited by tennis because it's also a powerful anabolic agent that promotes muscle growth. Puerta was suspended for nine months and was warned that a second conviction would result in a lifetime ban.

Another highly ranked Argentine, Guillermo Canas -- the player Puerta defeated in the French Open quarterfinals on his way to the final -- was recently suspended for two years after he tested positive for the diuretic hydrochlorothiazide. Diuretics increase the urine production in the body and are banned because they're often used as masking agents for other, more substantial, prohibited substances.

I had a good laugh when I read some of Guillermo Coria's quotes a couple weeks ago. Apparently, in addition to being the world's No. 6-ranked player, Coria is also Argentina's communications ambassador. He took offense to the assertion that Argentine tennis has a tainted image, even though four of his country's top players (Puerta, Juan Ignacio Chela, Canas and Mr. Coria himself) have all tested positive for banned substances in the past four years. Coria was adamant that the stereotype was exaggerated and that they were being unduly criticized.

It's pretty amusing that Coria somehow twisted it around to make it sound like he's the victim. The real victims in these situations are the fans, the sport and the players on tour. We already know Canas was only allowed to compete at the French Open while appealing his positive test a few months prior. And if Puerta did indeed test positive, who knows who rightly deserved to be competing against Rafael Nadal for the title last June?

When we players hear about one of our own testing positive, we can't help but wonder if we're all competing on an even field; it's frustrating to think we might not be. There are always rumors, accusations and innuendos in every sport, and most of the time they are just that. I'm no conspiracy theorist, but I have to believe that cheaters will always be one step ahead of the testing process.

Hopefully more athletes getting caught will indicate the gap is closing. It's sad that there will always be some people out there who are willing to sacrifice everything, even their own health, to achieve more.

The most annoying parts of these doping scandals, in every sport, are the lame denials that inevitably come from every positive test. It sure would be refreshing if just once, the athlete who has muscles popping out of his eyeballs just fessed up and said, "You caught me. The truth is, I'd prefer to win a few more trophies than have functioning kidneys."