That's probably overly optimistic for a biceps injury, with Roberts saying Garcia didn't feel much better Saturday than he did Friday. He figures to be examined by team surgeon Neal ElAttrache in Los Angeles on Monday.
"We feel we dodged a bullet," he said. "The biceps is more benign than the elbow."
Garcia has appeared in nine games this season and has a 3.24 ERA.
Roberts said the club, which expanded the bullpen to eight relievers in preparation for the demands of Coors Field, couldn't go "a pitcher short" in the remaining two games.
Roberts said Lee, a lifelong starter, would serve as the long reliever and free up Joe Blanton for situational shorter stints. Lee has gone 3-0 with a 1.56 ERA in three starts with Oklahoma City this season.
"Lee has been throwing well, and it makes sense that he performed and got rewarded," said Roberts.
Louis Coleman is expected back from a bereavement leave on Monday, so Lee's stay could be short as room will need to be made to activate him. Luis Avilan was called up to replace Coleman.
Ken Gurnick is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.