Lewis, a rookie fourth-round pick, has stepped up in his first season, starting four games at left guard and replacing injured first-round pick Ronnie Stanley at left tackle for four games. The Ravens aren't planning to immediately place Lewis on injured reserve, even though there are only seven regular-season games remaining.
"There's nothing imminent along those lines," Harbaugh said. "We're going to try to see where that goes in the next few weeks. Hopefully, we'll get him back."
Losing Lewis for a significant time is compounded by the fact that Baltimore has played without Pro Bowl right guard Marshal Yanda for three of the past four games. Yanda is dealing with a shoulder injury.
Harbaugh didn't offer any updates on Yanda.
"We'll let you know as we go and see how he progresses," Harbaugh said.