Justin Timberlake surprises Jessica Biel during Pilates ab session

Justin Timberlake couldn't contain his admiration for Jessica Biel's impressive abdominal muscles during a recent workout session.

The 42-year-old "Mirrors" singer surprised his wife by joining her during her intense Pilates ab workout, which she documented in a video posted on Instagram on Monday.

As Jessica Biel, 41, followed the ab series instructed by fitness coach Ashley Brown, a pair of sneakers entered the frame, indicating Timberlake's presence. Biel playfully hinted at his appearance by writing "guess who it is" in the video.

Timberlake then playfully poked at Biel's stomach, which she jokingly referred to as her "abs of steel," as she performed her exercises on the floor.

Amid the workout, the audio of Olivia Rodrigo's latest single "Vampire" briefly cut out as Biel pointed the camera towards Timberlake, stating, "That was my man."

The video concluded with Biel saying, "Have fun y’all."

This isn't the first time the former NSYNC member has joined Biel during her workout routines. In a video she shared on Instagram in June, Timberlake gave her a congratulatory high five after her challenging "cruel single leg squat" workout.

In a previous instance from February, while Biel was training with fitness expert Ben Bruno, she humorously mentioned that "some other guy" (Timberlake) wouldn't "stop distracting me," as seen in the caption of her Instagram post.