Reds manager Dusty Baker remained at Northwestern Memorial Hospital overnight for observation and further testing after tests Wednesday afternoon revealed an irregular heartbeat, Reds officials said.
The 63-year-old former Cubs manager won't return to Wrigley Field for Thursday's series finale.
A team spokesman said Baker reported feeling fine after the game and that he expects to rejoin the team Friday in Cincinnati.
Baker left the ballpark about two hours before the game to have precautionary x-rays in an effort to rule out pneumonia, the Reds said, after being checked by the Cubs' team doctor for a persistent cough.
Team officials indicated Baker has had some history of irregular heartbeat.
Cincinnati bench coach Chris Speier, a former Cubs coach, filled in for Baker Wednesday night.