Mariners manager Don Wakamatsu said he was encouraged by what he saw from Lee, who is on the 15-day disabled list with an abdominal strain and is expected to miss the first month of the season.
The 2008 Cy Young Award winner will throw a 60-pitch bullpen session Tuesday and a 35-40 pitch simulated game Friday. After that, Lee could go on a rehab assignment.
Erik Bedard, another injured left-handed starter, threw 45 pitches in a bullpen session Sunday. Bedard, who is on the 15-day DL recovering from left shoulder surgery, is scheduled to throw 55-60 pitches on Wednesday.