Chester missed practice Friday, but Harbaugh expressed confidence that the fifth-year pro would be ready to go this weekend against the Carolina Panthers.
"We think he'll be there for Sunday, but you never know with those things," Harbaugh told The Sun while acknowledging that he was unsure about the exact diagnosis.
"It's not serious, but it was something that was causing a lot of pain," Harbaugh said. "They're going to work on the infection and make sure it's OK."
Chester has started all nine games for the Ravens this season. He has appeared in 68 games during his career.
The Associated Press contributed to this report.