It's all Viv's fault!
Brad Pitt was rocking a cane at the Palm Springs Film Film Festival gala on Saturday night -- and he finally explained the injury (first revealed late last week) on the red carpet to Us Weekly.
"I was carrying my daughter [Vivienne Jolie-Pitt, 3] down the hill and I slipped and it was either her or me," Pitt, 48, told Us. "It's my ACL," he added of the knee injury, but added that no surgery is planned. "I think I will be alright!"
At his side at the event, love Angelina Jolie was quick to tell reporters that he's not asking for extra help around the house because of the injury.
"He is not that kind of guy," the In the Land of Blood and Honey director, 36, said. "He does everything! I like the cane!"
And little Vivienne (twin sister to Knox) is no worse for the wear either. "Vivi's okay. She was absolutely fine. He took the fall."
Jolie similarly hurt herself years ago with her eldest, Maddox, 10. "It happened when Mad was younger. I took a fall as well and cracked my elbow because I wanted to make sure he wasn't injured," Jolie said. "Every parent has injured themselves."
Among their six kids, the child of the weekend was Zahara, who turned 7 on Sunday. "We are focusing on birthday parties tomorrow for Zahara," Jolie added.