The move was not unexpected because the left-hander had been suffering from a lower right abdominal strain, sustained during a March 15 spring training game.
His placement on the DL was retroactive to March 26.
Trainers have prescribed rest after treating Lee with platelet-rich plasma therapy to speed up the recovery process. Mariners' officials said Lee had a pain-free workout last week but have nevertheless opted to delay his Seattle debut after acquiring him in an off-season trade with Philadelphia.
The Mariners on Sunday also selected designated hitter Mike Sweeney from Triple-A Tacoma and re-assigned pitcher Jesus Colume, catcher Josh Bard, and infielders Josh Wilson and Chris Woodward to minor league camp.
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