OWINGS MILLS, Md. -- Lamar Jackson doesn't know who is starting at quarterback for the Baltimore Ravens on Sunday, but the rookie first-round pick is set to make his first NFL start if called upon.

"I feel like I'd be very prepared," he said. "I'm trying to sponge everything in. ... Whatever happens, will happen."

Quarterback Joe Flacco, who is dealing with a right hip injury, didn't practice Wednesday or speak to reporters because he was undergoing treatment.

Coach John Harbaugh said earlier in the week that Flacco doesn't have to practice in order to start in Sunday's game between the Ravens (4-5) and Cincinnati Bengals (5-4). On Wednesday, Harbaugh declined to talk about his uncertain quarterback situation.

"I don't feel like we owe anybody any answers," Harbaugh said.

There is excitement building among the Ravens fan base to see Jackson, the No. 32 overall pick in this year's draft. He's the only one of the five first-round quarterbacks not to start a game this season.

Jackson, the 2016 Heisman Trophy winner at Louisville, is the only player in FBS history to rush for at least 1,500 yards and pass for at least 3,500 yards in consecutive seasons.

In nine games this season, Jackson has primarily run a Wildcat-style offense, completing 7 of 12 passes for 87 yards and a touchdown while ranking second on the team with 139 yards rushing.

Teammates say Jackson has more confidence in the offense at this point in his rookie season.

"He's just being a ballplayer now," receiver Willie Snead said. "Once he has the scheme and everything around him under wraps, you'll see the playmaker come out of him."

Harbaugh hasn't ruled out going with Robert Griffin III if Flacco is sidelined. Griffin, the No. 2 overall pick in the 2012 draft, has been inactive as the third quarterback all season and hasn't started a game since the 2016 season finale.

Even if Jackson gets the start, Griffin could see time to limit the pressure on Jackson.

"If I get that opportunity to go out there and play, I'm going to make the most of it," Griffin said. "Show these guys not only how hard I've been working but how much I believe in them. it's been awesome."

The biggest challenges for Jackson are accuracy and throwing from within the pocket. In three years as the starter at Louisville, Jackson threw for 9,043 yards and 69 touchdowns but he never completed 60 percent of his passes in any season.

Jackson looked raw in throwing the ball during the preseason, completing 50 percent of his passes. Jackson acknowledged that his passes wobbled, but he has a better handle on throws now.

"I was throwing a lot of ducks," Jackson said. "I was getting accustomed to that ball, that's all. It's different from college to the NFL pigskin."

Players have been impressed with Jackson's athleticism since joining the Ravens. Middle linebacker C.J. Mosley said in June that it's like watching a young Michael Vick when Jackson gets out of the pocket.

Cornerback Marlon Humphrey said Wednesday that it's difficult to defend Jackson when he's been running the scout team.

"Since he's been here, he's been way faster than what I would've thought on TV," Humphrey said. "What people don't see as much is he throws pretty well, especially when he scrambles."

Jackson's biggest growth has come in calling the plays in the huddle. When Flacco was running the offense in practices, Jackson would practice calling plays by repeating them to quarterbacks coach James Urban.

"Before I had to ask coach 100 times, 'Say it again, say it again,'" Jackson said. "Now, he'll say it one time to me. Sometimes, don't get me wrong, if it's longer, I have to say, 'Say it again.' But, other than that, I'm getting better at that."

Griffin, who has helped mentor Jackson on the field, joked that he never thought he would be a big brother at the age of 28.

"The thing I've tried to preach to Lamar is he's been doing this his whole life," Griffin said. "It's a new level. But the cream always rises to the top. I think he's done a good job of adjusting his level of play as he's gotten more and more game reps. That's what you want to see out of a young guy."

This marks only the eighth time that Flacco will be on the injury report in his 11-year career. It was also the fourth missed practice during the regular season for Flacco (when you exclude the time he spent on injured reserve in 2015).

Flacco injured his hip in the Ravens' last game, a 23-16 loss to the Pittsburgh Steelers on Nov. 4. He didn't miss any plays that game and said afterward the hip didn't affect his play.

"That's something that I hope he fans of Baltimore really respect -- Joe is tough," Harbaugh said. "His pain tolerance is high. He always wants to play. That's proven over the last 10½ years."