Mariners head trainer Rick Griffin said Monday the former AL Cy Young Award winner was scheduled to do rehabilitation in a swimming pool later in the day.
Lee has been suspended for the first five games of the regular season for throwing over the head of Arizona's Chris Snyder in a spring training game earlier this month, possibly delaying his highly anticipated debut with the Mariners.
Prior to the injury, Lee had been planning to appeal the suspension.
Another Mariners pitcher, Erik Bedard, had hoped to throw off a mound Tuesday, but that was called off. Griffin said Bedard is not yet ready and that long toss and throwing off flat ground will continue to be part of the lefty's rehabilitation process.
The decision is not a setback, Griffin said.
"He's so far ahead of where he's supposed to be," Griffin said, noting that Bedard is seven months into rehabilitation from surgery on his left shoulder, and that the normal recovery time is 10-12 months.
Bedard is hoping to be able to pitch again by June.
Infielder Jack Hannahan has a strained right groin but took ground balls on Monday.