Seattle manager Lloyd McClendon said an MRI revealed the extent of the injury, and that there is no timetable for when Saunders will return. Saunders said it initially felt like a muscle cramp and that it's not a sharp pain he's feeling.
Saunders was injured in the eighth inning Thursday night and had to be pulled from the game in the middle of the at-bat. This is Saunders' second stint on the DL after sitting out with a shoulder injury in June.
"Obviously, it's extremely frustrating for me," Saunders said. "That being said, it's something I'm going to have to deal with and do my best to get back in there as soon as possible."
The Mariners recalled first baseman Justin Smoak from Triple-A Tacoma to take Saunders' roster spot. Smoak was in the lineup Friday night for Seattle's series opener against Oakland.
Smoak was placed on the disabled list June 11 with a quadriceps injury and had remained in the minors after the conclusion of his rehab assignment. Smoak was hitting .208 with seven homers in 63 games before getting injured, but his average dipped significantly while trying to play through the leg injury.
"I tried to play through it a little bit but now the legs feel great," Smoak said.