While Rays manager Joe Maddon said he had no prior knowledge of the injury, Garza told the media following the game that the problem surfaced late last year.
"It's been gradually hurting, but I've fought it off," Garza said.
Faced with a difficult decision, the Rays' No. 3 starter said he got to the point where he couldn't continue to throw in pain.
"It's either mess it up or see what I can do and, hopefully, try to get out of this, or let somebody who's not in pain come in and take care of it," said Garza of his decision to alert the clubhouse.
Garza walked off the mound after walking Jose Vidro, and signaled on the mound for a trainer, with two outs in the top of the third inning. When the right-hander turned the ball over to Scott Dohmann, the Rays were trailing, 3-1. Dohmann got Kenji Johjima to ground out, but the Rays went on to drop the game, 6-5.
Garza said his arm pain was sharp, but did not come about from any particular pitch he threw on Tuesday. Garza threw 70 pitches, including 40 for strikes, and experienced a pain similar to someone pressing down on the outer part of his arm.
When he did alert the Rays to his predicament, the call was easy.
"He tightened up because of a nerve, and it didn't feel right," Maddon said. "So obviously, we're not going to let him pitch at that point."
The right-hander was acquired in the offseason in a trade with Minnesota, and was expected to be the No. 3 starter in a trio that included Scott Kazmir and James Shields. With Kazmir also on the DL -- sidelined since Feb. 25 with a left elbow strain -- the Rays have some decisions to make regarding next week's rotation.
Although Kazmir appeared to be on track in a live bullpen session prior to Tuesday's game, he is still expected to be back late-April at the earliest.
Following Garza's injury, Maddon said the rotation was "undetermined," but made clear that Jae Kuk Ryu, who was recalled from Triple-A Durham on Tuesday night, would not get Garza's expected April 13 start.
"No, he's just going to come in and pitch in the bullpen right now," Maddon said. "Tonight we used just about everybody ... if we need some bullpen help, we've got Jae Jae."
In the past with short-term injuries, the Rays have often called up the pitcher scheduled to pitch in Durham that night. That would mean Jeff Niemann, who received a favorable amount of time in the spring, would get the call.
Other options for the Rays could be to pull lefty J.P. Howell out of the bullpen and give him a spot start, but with Niemann already slated to pitch on Sunday, the lanky right-hander would be the most logical substitute.
Brittany Ghiroli is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.