On New Year's Day 2019, tennis greats Serena Williams and Roger Federer took the court as opponents.
It was an unusual treat for fans of the sport: the two superstars who separately dominated their own fields of women's and men's tennis were facing off against each other in a mixed doubles match.
But any competitive energy Williams and Federer wielded during the match melted away during a post-game interview, when they traded compliments and gleefully shared what it was like to play against the best in the world.
"For me, it was super cool," Williams said with a laugh. "I literally wanted to take pictures and wanted to bring my baby out. I'm, like, way too excited."
Federer was delighted, too.
"It was a bit nerve-wracking too, to be honest, because all of the sudden you're serving, especially the last serve at three-all, I'm like, 'I gotta win this point, but it's Serena Williams!'" he said to laughs from the crowd.
"And I was telling myself, this is maybe what I've always wanted, a big-time moment like this," Federer added, smiling.
Now Williams, 40, and Federer, 41, have both announced in short succession their plans to retire, leaving the tennis world without two iconic competitors who were among the best the sport has ever seen and whose appeal eclipsed the game.
Their retirements leave a 'gaping hole' in the tennis world
Jon Wertheim, a senior writer at Sports Illustrated and a Tennis Channel analyst, told NPR it's expected that given their ages, Williams and Federer plan to retire. But the announcements were still a shock.
"This is like the Sears Tower and the Empire State Building are both scheduled for demolition within a few weeks of each other," he said.
Last month, Williams announced on Vogue magazine's website that she would retire after this year's U.S. Open, saying that at her age, "something's got to give."
Federer's announcement came last week. He said his body's "message to me lately has been clear" and noted that his final competition would be this week's Laver Cup in London.
Williams and Federer have 23 and 20 Grand Slam titles, respectively, but neither player has won a major title in recent years.
The current top-ranked tennis players – Carlos Alcaraz of Spain and Iga Swiatek of Poland – are 19 and 21 years old. And men's tennis greats Rafael Nadal and Novak Djokovic are still in the mix, Wertheim noted.
"The sport has sort of moved by [Federer and Williams] on both the men's and women's side, but I think it's just this gaping hole in terms of what the casual fans think about when they think of tennis."
Williams' and Federer's influence went beyond the sport
For Williams, her impact comes not only from her athletic ability, but also her public coming-of-age as a Black woman in a historically white sport.
Williams and her sister, fellow tennis player Venus, have been criticized throughout their careers for their appearance, from Venus getting penalized in 1999 for her hair beads falling out to Serena being accused of disrespecting tennis after wearing a black catsuit during the 2018 French Open.
Akilah Carter-Francique, dean of Benedict College's School of Education, Health and Human Services, told NPR the Williams sisters have had to navigate a tennis world that wasn't always welcoming to them.
"The ism's were definitely out there, whether it be racism, sexism, classism. All of those things they had to battle in real time in front of us in a media-heavy space and endure that," she said. "They did that with such grace."
And because the star athletes also became cultural icons, Carter-Francique suggested their appeal extended not only to aspiring tennis players, but also young girls and women as well as Black youth and other youth of color.
"Here is a space that was not designed for them, but they came in and reimagined it, pushed the envelope, raised the bar in many ways, and influenced not only tennis culture but I think influenced pop culture," she said.
Federer, who began playing tennis at a young age like the Williams sisters, has been characterized by his effortless play style and his decency toward other players, fans and the media.
Djokovic, one of Federer's top rivals, said on Instagram that the Swiss player's career "set the tone for what it means to achieve excellence and lead with integrity and poise."
Now, with Williams and Federer on their way out, tennis moves into a new phase.
But Wertheim suggested that it could be in fact due to the contributions of the pair that tennis remains as popular and relevant as ever even as two of its biggest names move on.
"Maybe their legacy is ultimately that their individual loss won't really be to the sport's detriment, because they brought so many new people to the party."