Despite two failed doping tests this summer, Italian tennis player Jannik Sinner is on his way to the semifinals at the U.S. Open. 

Sinner will play England's Jack Draper Friday night for a chance to play in the men's singles final. The 23-year-old star is looking for his second Grand Slam title amid ongoing backlash against his eligibility for this year's tournament by the International Tennis Integrity Agency (ITIA). 

Sinner tested positive twice for a banned anabolic steroid in March. The anabolic steroid he tested for is called clostebol and is a derivative of natural testosterone. 

The source of the clostebol was a spray used for treating open wounds that is available without a prescription. However, the packaging of that spray has a large warning that says "DOPING." 

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The spray, Trofodermin, also contains an underlined warning in Italian on the medication guide that comes inside the box that says, "For those taking part in sports: use of the drug without therapeutic needs constitutes doping and can result in positive anti-doping tests."

Clostebol is listed in the anabolic androgenic steroids section on page 5 of WADA’s 24-page list of banned substances. Italian law dictates that all medications that include substances on the World Anti-Doping Association’s (WADA) banned list come with the printed "DOPING" warning.

Jannik Sinner takes a shot

Jannik Sinner returns a shot during the first round of the U.S. Open Aug. 27, 2024, in New York.  (AP Photo/Kirsty Wigglesworth)

San Diego Padres star Fernando Tatis Jr. was suspended by MLB for 80 games after testing positive for the same drug in 2022.

Sinner was not suspended because it was determined the clostebol entered his body during a massage from his physiotherapist, Giacomo Naldi, ITIA announced Aug. 20 after an independent investigation. Sinner said his fitness trainer, Umberto Ferrara, bought Trofodermin in Italy and gave it to Naldi for a cut on Naldi’s finger. Naldi then treated Sinner while not wearing gloves.

Clostebol is listed as a controlled substance in America, so it can only be sold with a doctor’s prescription because the U.S. government considers it to have a potential for abuse. 

Pending a potential appeal from the WADA, Sinner will get away with his physiotherapist's mistake. It's a decision that has already drawn criticism from some of the sport's top players.

Men's tennis superstars Novak Djokovic and Carlos Alcaraz have addressed the topic and criticized what they described as a lack of transparency. 

US OPEN WINNER ANDRE AGASSI BELIEVES AMERICAN TENNIS IS POISED FOR GRAND SLAM ‘BREAKTHROUGH’ IN MEN’S SINGLES

Jannik Sinner plays shot

Jannik Sinner of Italy plays a backhand during his match against Frances Tiafoe of the United States during the final day of the Cincinnati Open at the Lindner Family Tennis Center Aug. 19, 2024, in Mason, Ohio.  (Dylan Buell/Getty Images)

"We see a lack of standardized and clear protocols. I can understand the sentiments of a lot of players that are questioning whether they are treated the same," Djokovic told reporters ahead of the U.S. Open.

Alcaraz told reporters, "I think there's something behind this that a lot of people doesn't know. I don't even know. In the end, it's something very difficult to talk about." 

Meanwhile, Australian tennis star Nick Kyrgios, who won the Australian Open in 2022 but also lost to Sinner in the Miami Open that same year, took a stronger stance against his former opponent's eligibility. Kyrgios said Sinner only surrendering prize money and points is "ridiculous," and the Italian shouldn't see the court for a long time.

"Whether it was accidental or planned. You get tested twice with a banned (steroid) substance… you should be gone for 2 years. Your performance was enhanced. Massage cream…. Yeah nice," Kyrgios wrote in a post on X Aug. 21. 

However, some have come to Sinner's defense. 

Eight-time Grand Slam champion Andre Agassi defended Sinner in a recent interview with Fox News Digital.

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Jannik Sinner in action

Jannik Sinner of Italy wipes sweat from his face between serves to Mackenzie McDonald of the United States during the first round of the U.S. Open Aug. 27, 2024. (AP Photo/Kirsty Wigglesworth)

"If you're going to performance enhancement cheat, you're not going to put a billionth of a gram of something in your body on purpose. You're going to get a benefit from the performance enhancer if that's your objective," Agassi said.

"It's not like when you missed three tests, or you don't take three tests — like we've seen with a couple players — that's an immediate action, right? So, the quietness of it is always there in any due process, unless a player willingly chooses to talk about it. And his ability to play while it's being appealed, it's not necessarily a rule, it's a law."

Sinner became the betting favorite for this year's title when Djokovic and Alcarez were eliminated early in the men's singles tournament. After defeating 2021 U.S. Open champion Daniil Medvedev in the quarterfinals Wednesday night, Sinner is the only man left in the field who has won a Grand Slam title.

Draper and American Taylor Fritz are participating in the semifinals at a major for the first time. Fellow American Frances Tiafoe made it to the semis two years ago before losing to eventual champion Alcaraz.

Sinner has been to the semifinals at each of the four Grand Slams and is particularly strong on hard courts, where he is 33-2 with four titles in 2024.

The Associated Press contributed to this report.

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