With money for professional athletes at unprecedented heights, there has never been more temptation to cheat. Somewhere, as we speak, there is probably a cutting-edge chemist/doctor manipulating compounds, looking for a way to beat the dope-testing system.
The recent news has been depressing.
Baseball's Ryan Braun was suspended 65 games for use of performance-enhancing drugs. And the next Biogenesis wave threatens has engulfed a host of All-Star-quality players, from Alex Rodriguez to Nelson Cruz. It's the same in the NFL, where five players were suspended in July alone for violating the league's substance abuse policy, including Denver Broncos linebacker Von Miller.
American sprinter Tyson Gay won't be running in next month's world championships after reported multiple positive tests for an illegal substance, one at the nationals, where he won the 100- and 200-metre races.
Although this year's 100th Tour de France was widely believed to be the cleanest in the post-Lance Armstrong era, the sight of British cyclist Chris Froome charging up Mont Ventoux after 240 kilometers in the saddle inspired skepticism. Was he clean? "100%, 100%" the eventual champion answered after winning Stage 15.
Is it naive to think that tennis - a sport that requires extraordinary endurance and places unnatural physical demands on its most successful players - is any different? Yes.
After Armstrong admitted he had doped for years, 17-time Grand Slam singles champion Roger Federer used that precise word - "naive" - in suggesting that tennis is tainted by cheaters just like every other sport. Rafael Nadal, for example, has never failed a drug test, but there have been repeated, random whispers that his 12 major titles were built on a foundation of better chemistry.
We may never know the truth, for the International Tennis Federation, the sport's governing body, has been criticised repeatedly - even the French Senate's recent report weighed in - for a weak, shoddy oversight system.
Perhaps that's why it was so startling when two former top-15 players were recently flagged for alleged doping transgressions. Serb Viktor Troicki was given an 18-month ban for failing to provide a blood sample at the April ATP World Tour event in Monte Carlo. Two days after that announcement, reports surfaced in the Croatian press that Marin Cilic failed a drug test that same month in Munich.
Naturally, both players are appealing and have detailed explanations. In doping there is always a story. Troicki, who did submit to urinalysis, claims the doctor said it was OK to pass on the blood test. The doctor says otherwise. Cilic wasn't notified of the positive test until before his second-round match at Wimbledon, then pulled out, citing a knee injury. His status, heading into the Montreal event, is unclear.
What is the incentive to dope? Follow the money.
Last year, Russian Mikhail Youzhny, now 31, finished as the ATP's No. 25-ranked player. He won 33 of 54 matches and won $879,840 in prize money. He undoubtedly collected much more through endorsements and off-the-record guarantees from smaller events.
His counterpart among WTA players was Su-Wei Hsieh, a 27-year-old from Chinese Taipei who had never finished ranked higher than No. 79, but won two titles and ended the year at No. 25. She earned an official $490,114 in prizes-- more than the president of the United States, minus book royalties, made.
This is not to suggest they are doping, but to underline the potential rewards of the sport.
Tennis has a history with drugs. In 1998, six months after he won his first (and only) Grand Slam singles title, Petr Korda tested positive for the banned steroid nandrolone. In 2010, Wayne Odesnik pleaded guilty to importing human growth hormone into Australia and was banned from tennis for one year. In between, there were more than two dozen verified episodes with illegal substances.
Back in May, Spanish doctor Eufemiano Fuentes was tried for supplying cyclists with blood transfusions. During the "Operation Puerto" trial, Fuentes admitted that also among his clients were soccer players, boxers and tennis players. He didn't name names and, conveniently, the judge in the case ordered that more than 200 bags of blood and plasma being held as evidence be destroyed.
Andy Murray, for one, was baffled. "Puerto case is beyond a joke ... biggest cover-up in sports history?" he tweeted.
Fuentes got a year in jail. His unnamed clients got a reprieve when the evidence was destroyed.
The big four, including Nadal, have been pushing for stricter drug testing and more transparency in the process. They managed to push through some huge pay increases at the majors. The ITF would do well to listen to its leading players.
Greg Garber joined ESPN in 1991 and provides reports for NFL Countdown and SportsCenter. He is also a regular contributor to Outside the Lines and a senior writer for ESPN.com. This story first appeared on ESPN.com