Phillips was injured in the third inning of Tuesday's 7-6 loss to Pittsburgh when he tagged Gregory Polanco as he attempted to steal second base. Polanco was originally ruled safe on the play, but the call was overturned on a manager's challenge when it was shown Phillips had applied a tag on Polanco's left hip as he slid.
"He iced it last night and we hoped it would be better. He woke up, it was stiff and sore," Reds manager Bryan Price said.
Phillips played the whole game and went 2-for-5 with two singles and a run scored. He also tagged out Polanco attempting to steal again in the sixth. The runner was originally ruled safe, but the call was overturned again on a challenge.
Over 62 games this season, Phillips is batting .286/.323/.350 with three home runs and 26 RBIs.
Phillips' place at the top of the order was filled by center fielder Billy Hamilton, who was originally scheduled to bat ninth. Ivan De Jesus Jr. started at second base.
Last season, Phillips missed 33 games when he needed surgery to repair torn ligaments in the same thumb. Price did not believe there was any issue related to that previous injury.
"It just got bent back on that steal attempt last night and it bothered him a little bit," Price said. "We anticipated it would get better with treatment and a good night [of] sleep, and it didn't. We'll see him again and make sure everything is OK before he goes back out there."