Georges St. Pierre to undergo surgery on knee

Georges St. Pierre attends Marvel's

Georges St. Pierre attends Marvel's "Captain America: The Winter Soldier" premiere at the El Capitan Theatre on March 13, 2014 in Hollywood, California. (Charley Gallay/Getty Images for Disney/AFP)

, Last Updated: 8:18 PM ET

Even semi-retirement couldn't save Canadian MMA fighter Georges St. Pierre from another knee surgery.

St. Pierre, the former UFC welterweight champion who is on a self-imposed hiatus from the sport, tore the ACL in his left knee during a training session last week in Montreal. According to UFC Tonight, he will have surgery next week in Los Angeles, with Dr. Neal ElAttrache operating.

It will be the second time St. Pierre, 32, has needed knee surgery. He didn't fight for a year and a half after tearing the ACL in his right knee in 2011.

St. Pierre hasn't fought since UFC 167 in November, when he earned a surprising decision over Johny Hendricks to retain the UFC welterweight belt. He vacated the title in December to take some time off, citing pressures of being the champion among other things.


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