Jackson missed practice Friday, the third session he's missed after suffering an ankle injury in Week 14, and is officially questionable to play. Tyler Huntley would get the start Sunday if Jackson is eventually ruled out.
"I'd say he has a chance (to play)," Harbaugh said of Jackson. "It's just one of those things where it's an ankle sprain where if he starts feeling good, everything alright, we'll check him out prior to pregame -- he's in all the preparations and all that -- see where we're at.
"But if not, we got Tyler, and he'll be ready to go also."
Also questionable to play against Green Bay are receiver Marquise Brown (illness), tight end Nick Boyle (knee), offensive linemen Patrick Mekari (hand), Tyre Phillips (illness) and Alejandro Villanueva (knee) and fullback Patrick Ricard (back, knee). Defensive tackle Calais Campbell (thigh) is doubtful to play.
Jackson suffered the ankle sprain early in the second quarter of the loss to Cleveland. Harbaugh said earlier in the week it wasn't a high-ankle sprain, giving Jackson a chance to play this week.
Huntley previously started Baltimore's Week 11 win over Chicago. The QB completed 27-of-38 passing for 270 yards and a TD after replacing Jackson.
The Ravens will hold out hope Jackson can suit up Sunday as the 8-5 Ravens attempt to cling to the AFC North lead against the NFC-leading Packers.