San Francisco Giant's catcher Buster Posey is out for the rest of the entire season with broken left ankle.

He may have also torn his left knee ligament in the collision at home pate Wednesday night.

Posey, 24, was hurt during Wednesday night's 12th inning as he absorbed a home-plate collision with Florida's Scott Cousins, who scored the tiebreaking run in the Marlins' 7-6 victory. 

Eli Whiteside, Posey's backup, will become the No. 1 catcher. The Giants are expected to purchase the contract of Major League veteran Chris Stewart from Triple-A Fresno to add catching depth.

He was drafted by the Giants fifth overall in the 2008 Major League Baseball Draft. In July 2010 he earned both NL Player of the Month and NL Rookie of the Month honors. He was also named the 2010 National League Rookie of the Year.