The Los Angeles Angels right-hander Garrett Richards will be out six to nine months for a torn left patella tendon, the team announced Thursday.

An MRI confirmed the injury. Richards will placed on the 60-day disabled list and is expected to undergo surgery next week.

Richards suffered the injury Wednesday against the Red Sox. In the second inning, Richards ran to cover first base on a ground ball hit by Brock Holt. Angels first baseman Albert Pujols fielded the grounder and threw to second base for a force, but Richards never reached first to receive the relay.

He fell to the ground a few feet from the base after it appeared his left cleat got stuck in the dirt, twisting his leg awkwardly. Richards grabbed left knee and let out a loud scream.

"I was actually walking off and listening to him scream in pain," said Red Sox catcher David Ross, according to ESPN.com. "I got pretty sick to my stomach, as you can tell. That's a grown man out there screaming. Not a good feeling."

Replacing Richards on won't be easy for Los Angeles. He entered the game, which Anaheim won 8-3, with a record of 13-4 and a 2.61 earned-run average.