Randy Choate, who has been resting a fatigued right lat, threw off the mound on Saturday morning.
The session went well, and the veteran left-hander is scheduled to be back on the mound again on Monday.
Choate has yet to pitch in a Grapefruit League game.
If all goes well on Monday, the 36-year-old will face hitters in live batting practice on Wednesday, which is exactly two weeks before Opening Day.
The lost time, Choate says, should not prevent him from being ready when the season begins on April 4 against the Cardinals at Marlins Park.
"I don't think it will be an issue," Choate said. "I don't think it will take as long as [other relievers]. I've got one guy to get ready for, so I think I'll be in shape."
As a lefty specialist, Choate's role pretty much is to get left-handed batters out, which often means he will face one or two batters per outing.
Choate and Mike Dunn are expected to be the two late-inning left-handed options for Miami.
The team could carry a third left-hander in the bullpen, which may be Wade LeBlanc in a long-relief role.
In 2011, Choate was one of the Marlins' top relievers. He appeared in 54 games and had a 1.82 ERA in 24 2/3 innings.
Choate missed the final six weeks of the season after he was placed on the disabled list on Aug. 18 with left elbow inflammation. Choate said his elbow is fine, and the ailment that has slowed him in Spring Training thus far is on his right side.
In the first few days of camp, he was shut down before his second live bullpen session. Choate felt some cramping on his right side while taking some swings during batting practice.
"Arm-wise, I'm fine," he said. "We're just being cautious, getting a little extra time."
By next weekend, Choate could get back in Grapefruit League games. He is confident he will have enough time to be ready for the regular season.
"I'll throw a live BP [on Wednesday]," he said. "So I'd have more than a week and a half to get ready. I don't see it at an issue."