Aryna Sabalenka invited Barstool's Dave Portnoy to her player box for the US Open final

The president of Barstool Sports became a new tennis fan over the past week—and a big believer in the Belarusian (to the tune of $50,000 on one match alone).

You may know Dave Portnoy from Barstool Sports. You may know him from his beloved “One Bite” pizza reviews shot at slice shops around the country. You may know him as one of the most fervent and outspoken Boston sports fanatics anywhere.

And, over the past few days, you may know him as a tennis fan.

It was an unlikely union: Portnoy, the president of Barstool and millionaire many times over, boasts 2.9 million followers on X/Twitter, his timeline chock full of takes on the NFL, the NBA and other trending topics. Or with pictures espousing the allure of horse racing. Or with videos touting High Noons in Rhoback polos.

Tennis? @stoolpresidente was not exactly well-versed in the sport. But after attending the US Open for the first time on September 4, something happened. He talked about it in a blog post titled, “I Went To the U.S. Open for the 1st time. Here Is What You Gotta Know”. In it were gripes about the traffic—despite Portnoy having taken a helicopter from The Hamptons to Queens—high marks for the food at Flushing Meadows, a 7.7 rating of the Honey Deuce and, perhaps most surprising, a newfound love of tennis.

“I don’t know what I expecting but I loved the tennis,” Portnoy wrote. “It’s not just a good spectator sport it’s a great spectator sport. It’s better live than any other sport I’ve been too besides maybe courtside NBA.”

As a tennis fan, you always remember your first match. I was captivated at the sight, up close, of Gustavo Kuerten and Tommy Robredo trading flawless groundstrokes at the 2005 US Open. For Portnoy, it was Aryna Sabalenka who left an unmistakable impression.

The No. 1-in-waiting was at her ruthless best in the fourth round, dominating 13th seed Daria Kasatkina, 6-1, 6-3. Portnoy liked that.

“She was captivating to watch and I may bet on her for every match the rest of her life because she’s that good.”

That he did, and before you knew it, Portnoy became the unofficial president of the Aryna Sabalenka Fan Club. @stoolpresidente morphed into a stream of updates on Sabalenka’s progress, some not suitable for children. He even changed his profile picture to a celebrating Sabalenka.

The final didn’t go Sabalenka’s or Portnoy’s way, but both gave it their all—Aryna in New York City; Dave while in Tuscaloosa, Ala. for Barstool’s College Football Show.

Despite the loss, Sabalenka’s face still graces Portnoy’s X profile. But there’s an explanation for that, as he explained Sunday in an extended segment on Tennis Channel Live.

“Elon [Musk] won’t let me change my profile on Twitter,” he told Steve Weissman and Prakash Amritraj. “I’m not mad about it, but I’m stuck with her for the time being.”

Nevertheless, expect @stoolpresidente to continue commenting on tennis, tennis betting—and on his new favorite athlete.

“She was animated, I liked watching her, and I kind of fell in love with her style,” he said about Sabalenka. “I had 50 grand on her against Keys.”

It’s not just a good spectator sport it’s a great spectator sport. It’s better live than any other sport I’ve been too besides maybe courtside NBA. Dave Portnoy

He also let viewers know that Sabalenka was paying attention to him, too.

“She actually invited me to sit in her box, for the final,” said Portnoy, who due to his obligations in Alabama couldn’t accept. “I regret that. I think I would have been able to change the outcome and kept her calm a little.

“It also would have been me versus the entire stadium, and me versus the entire country.”