The visiting Blue Jays later announced that Kiermaier experienced discomfort in his right lower back. He was replaced in the batting order by Cavan Biggio.
Kiermaier, 33, is batting .319 with four homers and 15 RBIs in 42 games this season, his first with the Blue Jays. The three-time Gold Glove winner signed a one-year contract worth $9 million in December.
After the loss, the team said Kiermaier received treatment from Blue Jays trainers, and will do so again on Sunday.
The veteran had a tough season in 2022, as he was limited to 63 games with the Tampa Bay Rays because of injuries. He didn't play after July 9 and had a season-ending hip operation in August. He batted .228 with seven homers and 22 RBIs.
But, even in a season in which the Blue Jays have struggled under mighty expectations, Kiermaier has excelled and transitioned smoothly.
"I feel loved. I feel appreciated by my teammates, by fans. Coming here, everything's different. I knew one organization, one thing for so long. The transition coming over here was something I was anxious about," he told the Toronto Star earlier this month. "But excited, too, to see how me and my family were going to deal with it. And it's blown expectations out of the water. I'm having the time of my life. I really am."
Kiermaier is a career .251 hitter with 86 homers and 331 RBIs in 956 games with the Rays and Blue Jays.
Information from Reuters and the Associated Press was used in this report.