Officials at the Beijing Zoo are considering changes to keep visitors away from Gu Gu the panda.
For the third time, the panda has attacked a visitor who climbed into its space.
Officials say a man climbed a nearly 5-foot-high barrier to retrieve a toy dropped by his 5-year-old son.
A spokeswoman says Gu Gu, which weighs 240 pounds, clamped down on the intruder's leg and refused to let go.
Zookeepers had to use tools to pry open the animal's jaws. The victim suffered damage to major ligaments and is recovering from surgery.
In October, Gu Gu bit a teen intruder. And in 2007, he bit a drunken tourist who jumped into his pen and tried to hug him. The tourist retaliated by biting the bear in the back.