Both starters had been experiencing posterior right-shoulder soreness over the past couple days.
While it was noted following Saturday afternoon's 17-11 loss to the Jays that Niemann would not make his scheduled start on Sunday -- replaced by Andy Sonnanstine -- the development with Davis was unexpected.
Following his six-inning performance against the Twins on Thursday, where he surrendered six runs on ten hits, Davis said he felt fine. After a couple days of increasing stiffness, manager Joe Maddon and his training staff decided to send both Niemann and Davis back to Florida for precautionary reasons.
"Sure their is always concern," Maddon said. "These are two really valuable people and players for us. Again, Jeff keeps telling me, 'I feel better, I feel better, I feel better,' but then just doesn't get right over the hump, so we want to make sure. It's almost the same thing with both of them, they just need to be looked at. We all need to know that we're not going to hurt them by [overworking] them.
"We'll just know more after they're both examined [Monday], and we can make more definitive plans."
Davis, who was slated to start on Tuesday in Detroit, will likely be skipped in the rotation this time around in favor of Jeremy Hellickson.
Although nothing was set in stone, Hellickson was scratched from his start in Triple-A Durham on Sunday just in case the contingency plan came to fruition.
In his first Major League start on Monday against the Twins, Hellickson threw seven innings of two-run baseball en route to a 4-2 victory.