It has been more than two weeks since Baltimore Ravens middle linebacker Ray Lewis has played a game because of an injured right toe, but no one needed the break more than the team's 36-year-old defensive leader.
But Harbaugh made a point not to make any assurances of Lewis returning to face the Cleveland Browns this weekend.
"Ray is probably the guy that's the furthest away (from returning), if you're looking at all the guys," Harbaugh told the team's official website. "But then again, you never know. Ray has a sprained toe, a turf toe kind of thing, so those are a little more unpredictable."
The Ravens (8-3) surprisingly have flourished without Lewis. The defense experienced its ups and downs during a 31-24 victory over the Cincinnati Bengals, but Baltimore had nine sacks and yielded just two field goals in turning back the San Francisco 49ers 16-6 on Thanksgiving.
The Associated Press contributed to this report.