Garza, who left his April 8 start with radial nerve irritation in his right arm, said diagnosing the bothersome pain on his outer arm was crucial to his quick rehabilitation.
"I fought it all spring," Garza said. "Every bullpen I had to come in and do treatment with the trainers, kind of precautionary stuff, and I didn't want to do it because it hurt too bad."
The good news is the pain appears to have subsided. The righty said he was struck by how great it felt to throw pain-free on Tuesday, and credited the quick diagnosis by Dr. Koco Eaton, as well as a shot of cortisone for his short recovery.
When asked his return date, Garza was equally optimistic, saying, "When my [disabled list] time is up."
The first day Garza is eligible to be taken off the DL is April 24, the third game of the Rays' series against the Blue Jays in Orlando, Fla.
"I feel that good," he said. "That's my plan, but we'll see what's in store. Today is Day 1 of throwing off a mound. I felt good and I'm ready to get right back on it."
After a 30-pitch session, Garza will throw a more aggressive bullpen session on Thursday, and will follow that up with a simulated game. The 24-year-old said he hopes to avoid a Minor League rehab session, a possibility that manager Joe Maddon said the Rays are considering.
"Right now, it's looking pretty good," Maddon said. "You can just see the look on his face when he throws good, so we anticipate he's going to be pretty much on target in terms of getting back."
That's good news for the Rays, who are also without the services of ace Scott Kazmir. The southpaw is on the DL with a left elbow strain and is slated to throw around 45 pitches in a Class A Vero Beach game on Friday. If all goes well, Kazmir will be two Minor League starts away from making his regular-season debut.
Catcher Dioner Navarro, who has been sidelined with right hand lacerations, will catch Kazmir on Friday, and is expected to play in extended spring games Wednesday and Thursday.
Brittany Ghiroli is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.