McOwen, 24, who set a Class A California League record with a 45-game hit streak last season, suffered the injury while trying to catch a double off the wall by the Rockies' Clint Barmes in the bottom of the sixth inning. The Mariners said no one will know how much action McOwen will miss until after he is examined.
A sixth-round pick in the 2007 First-Year Player Draft, McOwen finished last season batting .340 with 10 home runs and 82 RBIs. He spent most of this spring in Minor League camp, and was 0-for-4 in Spring Training games with the big league club this year.
Thomas Harding is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.