Fiers exited soon after being hit in the left shin in the second inning, and the Detroit Tigers relied on their bullpen to beat the Cincinnati Reds 7-4 Wednesday for a two-game series sweep.
"That was supposed to be easy," Tigers manager Ron Gardenhire said.
Fiers was struck by a liner from Mason Williams, who wound up with a single when the ball caromed toward the first base line. Fiers finished the inning but didn't come out for the third.
"It wasn't too bad — it is just a bruise — but I couldn't really land on it," Fiers said. "The guys here didn't want to risk me changing my delivery and hurting my arm."
X-rays on Fiers' shin were negative. It was unclear whether he will make his next scheduled start.
"We're going to see how he is," Gardenhire said. "It swelled up pretty big."
Drew VerHagen (2-2) followed as the first of six relievers and pitched three scoreless innings.
"He had his good sinker going tonight, and that's tough for a hitter to get the barrel on," Tigers catcher John Hicks said. "Even if they do make contact, they are going to drive it into the ground."
Shane Greene pitched the ninth for his 23rd save in 26 chances.
Sal Romano (6-9) allowed four runs and eight hits in 5 1/3 innings.
Jose Iglesias hit a two-run double in the second, and Jim Adduci had a solo homer in the fourth.
Detroit made it 6-0 in the sixth when Ronny Rodriguez hit an RBI double and scored on Iglesias's single over a drawn-in infield. A throwing error by left fielder Phillip Ervin allowed in another run.
Cincinnati also threw away two relay throws to the plate, both allowing runners to advance on the bases.
"That was just bad baseball," Reds interim manager Jim Riggleman said. "It is a great effort, but bad performance. We have to find a way to clean that up."
Cincinnati closed to 6-4 in a four-run seventh, starting the inning with six consecutive hits off Alex Wilson that included Preston Tucker's RBI single and Curt Casali's two-run double.
Billy Hamilton added an RBI single off Louis Coleman, but Casali was thrown out at the plate by Rodriguez from first when he tried to score on a groundout.
"It was just not a good baserunning play on my part," Casali said. "The hesitation cost me. I wish I could go back because that was a rally-killer on my part."
Rodriguez, who replaced Adduci in the sixth, finished with two hits and two runs. Adduci also had two hits, including the homer.
"That's a great strategy, I guess," Gardenhire said. "They went to the lefty, and Rodriguez was the obvious move, but he made me look good."
JaCoby Jones, who forced Joey Votto at second on an apparent bloop single in the top of the eighth, had an RBI single in the bottom of the inning.
"I put my hand up like I was going to catch it, and that froze him," said Jones, a converted shortstop. "After that, I was just playing it like an infielder and trying to make a good throw."
Reds: With OF Scott Schebler (right shoulder) still waiting to start a rehab assignment and OF Jesse Winkler having season-ending shoulder surgery on Tuesday, Tucker was Cincinnati's designated hitter and will see action in the outfield.
Tigers: LHP Francisco Liriano is scheduled to start Sunday in Oakland. The allergic reaction that caused him to miss his first start after the All-Star break was finally determined to be caused by a chemical used on his lawn in Miami.
Reds: RHP Tyler Mahle (7-8, 4.53) starts Thursday at Washington, with RHP Max Scherzer (14-5, 2.30) starting for the Nationals.
Tigers: LHP Blaine Hardy (4-3, 3.61) starts Friday at Oakland. LHP Brett Anderson (2-2, 5.55) opens for the Athletics.