"The shots for his back went well today," Maddon said.
Maddon said he wants to see Percival go through a test run before deciding whether to put him on the postseason roster, noting that it is critical that Percival is able to pitch on back-to-back days.
"We're just going to have to make sure that he's healthy," Maddon said.
Percival has become a recent target of boo birds at Tropicana Field, which can largely be attributed to the fact the Rays closer has a 6.89 ERA with nine saves in 19 second-half appearances after posting a 3.54 ERA with 19 saves in 29 appearances during the first half.
"One thing people have to understand, we would not be in the position we are in without him, period," Maddon said. "He really set up this entire first-half run that we got on. Second, he's a very team-oriented person. If he doesn't feel he can help us, he'll be the first guy to tell us -- the first one to say, 'Listen, I am not ready to do this and we need to do something different.'
"And conversely, I believe it's at the point now where if he legitimately thinks he can help us, he would tell me so and I would believe him. So we're just going to have to see how that works the next couple of days. These shots, this second round, might really improve [his back] dramatically."
Maddon added that it is possible that Percival could be on the postseason roster and not be used as the closer.
Bill Chastain is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.