Watch Demi Lovato 'knock out' Sylvester Stallone in boxing session

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He might have played the most famous boxer in movie history, but Rocky star Sylvester Stallone found his latest opponent too tough to handle.

Singer Demi Lovato showed she has a mean right hook as she knocked down the veteran Hollywood star during a sparring session at an LA gym.

Demi Lovato (Richard Shotwell/AP)
Demi Lovato (Richard Shotwell/AP)

"Just knocking out Rocky (@officialslystallone) easy day at @unbreakableperformance," the 24-year-old posted on Instagram.

In the video, Sylvester, 70, can be heard joking, "I slipped! I swear, it was an accident!"

Moments later, the duo showed there were no hard feelings by embracing in a hug.

Sylvester shared the same clip to his own Instagram, writing: "Rocky gets knocked out by his long-lost daughter, Roxana ... Starring Demi Lovato @ddlovato. The Unthinkable At Unbreakable."