Serena Williams and Caroline Wozniacki are friends and former World No. 1s in singles, and on Monday they became doubles partners for the first time, teaming to win a first-round match at the ASB Classic in Auckland, New Zealand.
Williams and Wozniacki overwhelmed Japan's Nao Hibino and Makoto Ninomiya 6-2, 6-4 in a match that was both historic and poignant.
The pair jointly have won 24 Grand Slam titles and 102 WTA singles titles. Williams additionally has won 23 doubles titles, including 13 Grand Slam and three Olympic titles, mostly in partnership with sister Venus.
Serena hasn't played doubles with anyone other than Venus since 2015 and last played a WTA tournament with anyone other than Venus in 2002.
Wozniacki hasn't played doubles at all in the past three years.
But the pair have long harbored a desire to take the court as a doubles pairing, and on Monday they took what may be their last opportunity to do so.
Wozniacki is playing the Auckland tournament for the sixth straight year as a prelude to the Australian Open, after which she will retire from competitive tennis. She was diagnosed with rheumatoid arthritis shortly after winning at Melbourne Park in 2018 and has decided to make the Australian Open her last professional tournament before retirement.
Wozniacki and Williams will face each other one last time in an exhibition match in Copenhagen in May, which will be Wozniacki's tennis farewell.
On Monday, the pair formed a relaxed and intuitive combination, laughing and exchanging high-fives as they swept past Hibino and Ninomiya in 70 minutes.
"It was so much fun, I really enjoyed that," Wozniacki said. "I've been around for a long time and to get to play with Serena was amazing.
"It wouldn't be the same if I didn't at least once get to play with her on the same side. She's beaten me a lot of times on the other side, so it's actually nice that we can win together for once."
Williams added, "It doesn't seem like she hasn't played in a long time because she played unbelievable.
"It's cool. I can't let the rest of both of our amazing careers go without playing with her. With her doing so well as a Grand Slam champion and a longtime No. 1 for so long, of course I want to share the court with her."
Earlier, American teenager Coco Gauff beat Slovakia's Viktoria Kuzmova 6-3, 6-1 in 61 minutes to stay on course for a quarterfinal meeting with Williams.
Williams, the top seed, will play Camila Giorgi of Italy in her first-round singles on Tuesday, and Wozniacki will play New Zealand wild card Paige Hourigan.