Lee is currently waiting for a second opinion on his elbow by Dr. James Andrews after experiencing discomfort after throwing two innings in his spring debut last Thursday.
The 36-year-old underwent an Anthogram MRI, and a team physician noticed "little to no changes" in the elbow area. Andrews will review the same MRI.
Lee said if he needs to undergo surgery, "This season will be done, possibly my career, I guess. I don't know. We'll have to see."
On Sunday, the team said he will likely resume throwing on Monday, but he has been scratched from his scheduled Tuesday start.
Lee pitched in only 13 games last season due to elbow injuries that limited him, going 4-5 with a 3.65 ERA.The four-time All-Star won the Cy Young Award in 2008.
GALLERY: CLASSIC PHOTOS OF CLIFF LEE
- Molly Geary