He will throw one or two more times and graduate to his first bullpen session since March 18, when the pain in his side resulted from a collision with the Diamondbacks' Chris Snyder while backing up home plate.
"I feel good," he repeated on Sunday. "I virtually threw as hard today as I can throw and didn't feel anything. It's good."
That being said, Lee added that he wouldn't know until he actually is "on the mound pitching in a game" that the injury is behind him.
Manager Don Wakamatsu and the Mariners have their fingers crossed that it happens much sooner than later.
This is the third time in Lee's career that he's had an abdominal injury. He was sidelined for six weeks the first two times, but it could be less this time, thanks to a procedure that was not previously available -- a process in which a patient's own blood is removed and injected into the injured area.
Meanwhile, the five-game suspension Lee received for throwing a pitch over Snyder's head later in the March 15 game remains unresolved. Lee is appealing the suspension.
The case was originally scheduled to be heard via a conference call on March 28 but was postponed because a Major League Baseball official was unable to make the appointment.
Lee has been informed that the hearing has been rescheduled for April 14.
"But that is tentative, I believe," he said.
Lee being placed on the 15-day disabled list was one of six moves the Mariners made on Sunday to finalize the 25-man Opening Day roster.
The Mariners also selected designated hitter Mike Sweeney from Triple-A Tacoma and re-assigned pitcher Jesus Colome, catcher Josh Bard and infielders Josh Wilson and Chris Woodward to the Minor League camp.
Sweeney, a non-roster player invited to camp, signed his Major League contract on Sunday morning with general manager Jack Zduriencik looking on.
"Here, I'll literally take my hat off to Mike Sweeney," Zduriencik said to reporters, removing his cap. "It's a reflection on what he did to prepare himself. Often that goes unnoticed. He said, 'You have no idea how much this means to me.' I said, 'Mike, you have no idea how much it means to us.'"
Wakamatsu said before the final Spring Training game that left fielder Milton Bradley, who left Saturday's exhibition game against the Rockies in Albuquerque with a tight quadriceps muscle in his right leg, apparently is fine.
"He's not playing [against the Giants], but I expect him to be in the lineup [Monday] night," Wakamatsu said.
While Lee was playing catch on flat ground, left-hander Erik Bedard was throwing a bullpen session close by -- and looking terrific.
He threw all of his pitches and appeared to be throwing close to 100 percent, a pleasant sight to the Mariners, who could get him back sometime in May.
"Erik is progressing very nicely," Zduriencik said.