Earlier this month, Serena Williams caused a frenzy in the tennis world after it was revealed that she had re-entered the International Tennis Integrity Agency’s drug testing pool, a mandatory step for players looking to compete. While the American has since brushed off rumours of a comeback, former ATP Pro John Isner recently speculated about her potential return to the sport despite her firm denial.Williams is undoubtedly one of the greatest tennis players the world has ever seen. Her career on the courts spanned well over two decades and her list of accomplishments include 23 singles Grand Slam titles as well as 16 Major doubles trophies. Despite retiring over three years ago, the 44-year-old continues to be under the spotlight.Recently, during an episode of the Nothing Major podcast, John Isner reflected on the possibility of Serena Williams returning to tennis, saying,“Yeah, I think she’s a little bit annoyed. It's Serena Williams, right? She's always under the spotlight. So to me it's like why would you put yourself back in the drug testing pool? I mean, I'm not saying she's like definitively coming back, but maybe she's just leaving the door open to possibly come back in some form or fashion. Maybe it's just doubles. Who knows, right?”Isner went on to add that the American legend might be ensuring she has her ducks in a row in case she does decide to comeback, explaining,“I think for her, she was like, "All right, well, if I decide to come back, it's there for me. I'm back in the drug testing pool. It doesn't mean I'm coming back definitively, but I do have that opportunity.” You got to reenter (the pool). six months window or something like that. So she'll be eligible right away. So, she's just sort of getting her ducks in row in case she does want to come back. But that doesn't mean she is.”While Williams has denied speculation about her return, the American failed to provide an explanation for her return to the International Tennis Integrity Agency's drug testing pool.Serena Williams' ten-word response to rumours about her comebackWilliams at the 2025 Baby2Baby Gala (Image Source: Getty)Only hours after it was announced that Serena Williams had re-entered the drug testing pool, the American jumped on X to deny the rumours of her return. The 44-year-old penned a short note to address the matter, writing,“Omg yall I’m NOT coming back. This wildfire is crazy-”Serena Williams was last seen in action at the 2022 US Open. At the event, the American kicked off her campaign with a win over Danka Kovinić. She followed this up by upsetting World No.2 Anett Kontaveit in her second round, before eventually falling short against Ajla Tomljanović. Williams also competed in the women's doubles event at the 2022 US Open alongside her sister Venus Williams, with the pair losing to Lucie Hradecká and Linda Nosková.