Kiermaier was not in the starting lineup Friday for the fourth game in a row, but he did enter the game in the seventh inning, a sign his neck has improved. He struck out in his only at-bat during the Rays' 11-4 win over the Angels.
Tampa Bay remains a half-game behind the Oakland A's for the top American League wild card and one game ahead of the Cleveland Indians for the second wild card.
Kiermaier got back on the field a day after he was treated by the Rangers' chiropractor, Jerrod Wright, while the Rays were in Texas.
"An absolute game-changer," Kiermaier told reporters. "The adjustments we're doing are huge for what I need to do. Kind of get some joints back to where they need to be, back in place, alignment.
"I've already made crazy, crazy strides forward but still have a lot of muscles that are inflamed and whatnot. Still not feeling quite where I want to be, but the progress I've made the last 24 hours has made me a happy man."
Kiermaier has struggled of late, hitting .147 (5-for-34) in his past 12 games. In Kiermaier's place, the Rays have started Guillermo Heredia (three times) and Avisail Garcia (once) in center field.
Kiermaier is hitting .267 (4-for-15) with one triple and two RBIs in five games against the Angels this season, and .214 (18-for-84) with six extra-base hits and nine RBIs in 25 career games against them.
Right-hander Tyler Glasnow (6-1, 2.15 ERA) will start for Tampa Bay on Saturday, just his second outing since returning from a forearm strain that kept him out four months.
He was on a limited pitch count Sunday against Toronto in his return, and the same will be true on Saturday. Against the Blue Jays, Glasnow gave up two runs on one hit and two walks in two innings. Of the six outs he got, five were by strikeout.
Glasnow's lone career appearance against the Angels with a three-inning relief stint last year, when he gave up one run on two hits.
Los Angeles' Saturday starter, right-hander Jaime Barria (4-8, 6.14), will oppose the Rays for the first time in his career. It's been a rough sophomore season for Barria, who impressed the club last year when he went 10-9 with a 3.41 ERA in 26 starts.
Barria points to manager Brad Ausmus' use of an "opener" in some of his appearances this year as a potential reason for his struggles. Barria's ERA in the six games he entered after an opener started the game is 8.87. In the 10 games he has started, his ERA is 4.88.
His two worst games of the season came when the Angels used an opener. Barria gave up seven runs and 10 hits in 1 2/3 innings at Kansas City on April 27, and he allowed 10 runs and nine hits in 3 2/3 innings at Seattle on July 19.
"The opener is practically the only thing that has not worked for me," Barria told the Los Angeles Times. "It's new to me, it's a different role. It's not the same routine you keep. But when I do start games, it's worked out better for me."
Angels center fielder Mike Trout was expected to return to the lineup Friday but instead was on the bench for the sixth game in a row -- other than one pinch-hitting appearance -- because of a nerve issue in his right foot. He remains day-to-day.
--Field Level Media