Venus and Serena WIlliams. Photo: Frazer Harrison/Getty

Serena Williams says it was “very difficult” to compete against her sister Venus before retiring from tennis.

While speaking to PEOPLE at the 2024 Tribeca Festival premiere of her docuseries, In the Arena: Serena Williams presented by Morgan Stanley, Serena, 42, says she and Venus, 43, no longer have a competitive relationship now that they aren’t dueling it out on the tennis court.

“I didn’t really like it,” Serena says of competing against her sister. “I didn’t like to compete with your best friend. It’s very difficult.”

Serena teases that the subject of her and Venus in competition comes up in the upcoming eight-episode docuseries. “You’ll see that in episode two,” she promises.

Venus and Serena Williams. Julian Finney/Getty

“But some people like it,” Serena remarks about competing against siblings. “Some people are like, ‘I want my sibling to go down.’ And I’m like, ‘I want her to win too,’ and so it was very difficult. It was very hard.”

Serena softly retired in September 2022 after the U.S. Open, where she received an emotional send-off after losing to Ajla Tomljanovic in the third round. However, the tennis champ has since teased a return to the court on a handful of occasions.

Serena Williams.Michael Loccisano/Getty Images

During an appearance at TechCrunch Disrupt in October 2022, she clarified that she is “not retired,” according to The SF Standard. “The chances of me returning are very high,” Williams said. “You can come to my house and [see], I have a court.”

At Thursday’s premiere of her docuseries, Serena spoke highly of young tennis star Coco Gauff and joked, “Let me ask my knees,” when asked if she and Gauff, 20, would ever play a match.

Serena tells PEOPLE that while her “competitive craving” still exists, she’s focused on other aspects of her life — like being a parent to daughters Adira, born in August 2023, and Olympia, 6½, with her husband, Alexis Ohanian, 41.

In the Arena: Serena Williams premieres on July 10 on ESPN+ and promises to give viewers “the most complete, intimate, and compelling account of her legendary career,” through “firsthand perspective” from the tennis champion herself and “key figures” from her life.