The 38-year-old singer shared clips Wednesday on Instagram of her dancing to the 2018 single, which appears on Timberlake's album Man of the Woods.
The video shows Spears wearing a belly-baring white crop top and shorts. She referenced her highly-publicized breakup from Timberlake in the caption.
"This is my version of Snapchat or TikTok or whatever the cool thing you're supposed to do these days!!!!!" Spears wrote. "As you can see I'm not really dancing folks...... I'm just very bored."
"PS I know we had one of the world's biggest breakups 20 years ago...... but hey the man is a genius!!!! Great song JT!!!! Psssss if you KNOW WHAT'S GOOD!!!!!!" she added.
Timberlake responded in the comments with a tears of laughter and three raised hands emojis.
Spears and Timberlake both got their start as Mouseketeers on The All-New Mickey Mouse Club. The pair both skyrocketed to fame as teens, with Spears performing as a solo singer and Timberlake as a member of the boy band 'N Sync.
Spears and Timberlake started dating in 1999 and split in 2002. Timberlake fueled rumors that Spears had cheated by featuring a Spears lookalike in his "Cry Me a River" music video, released in 2002.
In a 2017 interview with Entertainment Tonight, Timberlake's former 'N Sync bandmate Lance Bass said a Timberlake-Spears collaboration would be "amazing." Bass said Timberlake and Spears are on good terms today.
"I would love to see it happen, and I don't think it's not going to happen," Bass said of a potential collaboration between the exes. "They're good. They're friends."