After hitting in the batting cages on Saturday, Lee hit on the field and took ground balls before Sunday's game.
"He's feeling really good," manager Brad Mills said. "He ran in the pool yesterday. We're going to think about getting him outside today and running. I don't know exactly where they are with that."
Lee strained his left hamstring running to first base on June 1 and went on the disabled list on June 3. He said he'll continue to listen to the trainers' advice, and he'll be eligible to return to the team in a week.