On Monday, he made the decision to ditch switch-hitting and become a full-time right-handed hitter. The move surprised Gardenhire, but Hicks went 2-for-4 that afternoon. However, he went 0-for-2 with a strikeout Tuesday night before Josmil Pinto replaced him in the lineup.
Hicks was listed in the ninth spot of the order until roughly two hours before Wednesday night's game, when Gardenhire replaced him with Danny Santana.
"He felt a tweak in his back a little bit during early BP," Twins assistant general manager Rob Antony said. "And then when he was taking regular BP felt it more. So he stopped at that point, went in and got treatment. Don't think it's anything more than a back spasm, but we'll have to wait and see."
Hicks spoke with the media after the Twins' 1-0 loss to the Rangers on Wednesday night. He confirmed the team's report of back spasms, citing a similar injury he suffered while playing in the Minors.
He said that he felt fine coming to the park in the afternoon and had no issues during early batting practice. When he began regular batting practice later on, however, he felt his back stiffen up on the lower left side.
"It was uncomfortable to swing," Hicks said. "Usually swinging right- and left-handed, I usually even it out. I might've overworked it."
There is currently no official timetable for his return, and Hicks said he is not sure whether he will be available for Thursday afternoon's game against Texas at Target Field.
Hicks is batting just .195 this season, but the Twins will miss his glove.
He made a diving catch on Monday and then followed that up with what he called the best catch of his career to rob Donnie Murphy of a home run on Tuesday night.
"I looked back and saw the ball originally," Hicks said. "But as soon as I was getting ready to jump, it changed direction and I kind of had to go over my head a little bit to catch it."
The play saved a three-run home run, and while the Rangers still scored two during the half-inning, the one-run difference proved to be enough for a 4-3 walk-off victory.
Gardenhire said has seen a more laid-back version of Hicks since he made the decision to ax switch-hitting.
"He's kidding around and joking around more than ever," Gardenhire said before the injury was announced. "You can tell that he's more relaxed. There's no doubt about that."