ATLANTA — Cliff Lee's stay on the disabled list may not be much longer than the mandated 15 days.

Lee threw what he termed a pain-free bullpen session Wednesday at Turner Field, taking the next step in his recovery from a strained left side.

"I didn't feel anything," Lee said.

The lefthander said he is scheduled to throw another bullpen Saturday. If that goes well, he could be activated to start sometime next week.

"That's the plan," Lee said. "That's always flexible."

Kyle Kendrick will take Lee's turn for the third time in Friday's series opener against Stephen Strasburg and the Washington Nationals.

Lee said he experienced no pain throwing the baseball. He can barely feel the strained muscle during a few exercises, but believes rest cured the issue.

Contact Matt Gelb at mgelb@phillynews.com or follow on Twitter @magelb.