Jon Lester, scratched from his last start because of a tired arm, threw a bullpen session on Monday.

The left-hander, who signed with the Chicago Cubs as a free agent this offseason, is confident he'll be ready to start on Opening Day.

"Today was more getting out there, getting my feet under me and going through my normal routine," Lester said. "The other stuff will be there. We're still in the process of building arm strength and arm speed, and that will come as the innings get higher.

"I've always felt it takes me a little longer, maybe toward the end of May, when you feel strong -- you feel good and just go through the five days with the games, throwing 100 something pitches every fifth day. It takes some time to where you're consistent with everything."

Lester is not worried about velocity, just building arm strength and staying healthy. He was scheduled to start on Thursday for the Cubs.