McCutchen returned to the team hotel in Atlanta and was placed on the COVID-19 injured list.
The Brewers recalled infielder Mike Brosseau from Triple-A Nashville, but it was not known if he would arrive in Atlanta before the start of Saturday night's game against the Braves.
Milwaukee manager Craig Counsell said McCutchen, 38, reported symptoms on Saturday.
Counsell said it was not yet known if McCutchen will remain in the Atlanta hotel when the team leaves after Sunday's game to begin a series in Cincinnati on Monday.
"We're trying to figure out what to do," Counsell said, before adding the continued battles with the coronavirus are "here this year for every team. We're not the only team by any means. We just saw Cincinnati got hit hard with it."
McCutchen had a single and scored a run while starting in left field in the Brewers' 6-3 win over the Braves on Friday night. He is hitting .240 with two homers and 14 RBIs.
Tyrone Taylor started in left field in Saturday night's game.