Johnson, averaging 21.5 points and selected to the All-Star Game for the third straight season, did not travel to Minnesota for Wednesday's victory and was not well enough to rejoin the team in Charlotte.
Coach Mike Woodson said he was holding out hope that Johnson will be healthy enough to play Saturday against the Los Angeles Clippers.
"He's feeling better, but we won't know his status until we get back [to Atlanta]," Woodson said. "He doesn't miss too many games, so he had to be pretty sick."
Maurice Evans got his second straight start in Johnson's place against the Bobcats.