MONTREAL - UFC welterweight champion Georges St. Pierre is out for 10 months with a torn knee ligament and will not defend his welterweight crown against American Nick Diaz at UFC 143.

The Montreal fighter's coach, Firas Zahabi, confirmed the news to QMI Agency Wednesday after UFC president Dana White issued a tweet earlier in the day.

Zahabi said St. Pierre (22-2) tore the anterior cruciate ligament in a knee and will undergo surgery.

"Various options are available to us, including synthetic tissues or those from a cadaver," he said. "Obviously we're disappointed, but in our sport these things happen."

St. Pierre, 30, was to defend his 170-pound welterweight title Feb. 4, during Super Bowl weekend. White says American Carlos Condit will take St. Pierre's place against Diaz, but only for an interim title.

St. Pierre initially was injured in October, which forced him to pull out of his planned duel with Condit (27-5, 13 KOs) at UFC 137.

He's one of UFC's superstars and has won nine consecutive fights, including six title defences.