Josina Anderson reports that Lamar Jackson will look to kick-start a struggling Ravens offense in place of the injured Joe Flacco (0:33)

BALTIMORE -- The Lamar Jackson era began Sunday after one of the strangest weeks in Baltimore Ravens history.

Jackson got the start for the injured Joe Flacco in Sunday's critical game against the Cincinnati Bengals.

Jackson's first NFL start gives Baltimore a chance to observe the player it drafted to be its quarterback of the future in a game that will significantly determine the Ravens' playoff fate.

Flacco came into Sunday listed as doubtful on the injury report, then was listed as inactive. He will not require surgery on his injured hip, a source told ESPN's Adam Schefter. He could miss the Ravens' game at home Nov. 25 against the Raiders as well, according to the source, but is not expected to miss time beyond that.

With Jackson the starter, Robert Griffin III, the No. 2 overall pick in the 2012 draft, is the backup quarterback against the Bengals.

Jackson's first NFL start comes after a surprise-filled stretch of days in which the Ravens saw Flacco walking on crutches for a hip injury and sent Jackson to the hospital after he suffered stomach issues.

"If you made this into a movie, no one would believe it," one team official said Friday.

Jackson becomes the last of the five quarterbacks drafted in this year's first round to start. Unlike the other rookie quarterback starters, Jackson stepped into a high-pressure situation, as the Ravens (4-5) have lost three straight games and are fighting for their playoff lives against the Bengals (5-4).

The first twist in the Ravens' quarterback drama came at the end of last week, when it was revealed that Flacco's status was uncertain because of the hip injury he suffered in a Nov. 4 loss to the Pittsburgh Steelers. The next unexpected turn occurred Thursday, when the team learned of Jackson's illness just before the start of practice and took him to a hospital for precautionary reasons. That left Griffin, the only healthy quarterback on the roster, to handle all the reps at practice.

Sunday's change at quarterback represents a drastic shift for the Ravens, who go from one of the most experienced quarterbacks in the NFL to the youngest starting quarterback in franchise history. Jackson, 21, becomes Baltimore's first rookie starting quarterback since 2008, when Flacco jumped to the top of the depth chart because of injuries to Kyle Boller and Troy Smith.

Jackson, who has been used in specialty packages, gets his first extended action against a Bengals defense that has been historically bad. Cincinnati is the first defense to allow more than 500 yards in consecutive games in the Super Bowl era.

Entering Sunday's game, Ravens coach John Harbaugh said he has seen "tremendous development" in Jackson.

"He's working every day, right through training camp, right through the season, at practice and then extra after practice, meetings," Harbaugh said. "[He's a] very diligent, very smart, very aware quarterback. He sees the game well, and then now all the process that goes into just training that eye has been valuable. So we have seen improvement, and in practice, he looks good."

In this year's draft, the Ravens traded into the first round to select Jackson, the 2016 Heisman Trophy winner. Jackson is the only player in FBS history to rush for at least 1,500 yards and pass for at least 3,500 yards in a season. Jackson accomplished this feat twice (in 2016 and 2017).

He went 22-11 as a starting quarterback at Louisville and was a touchdown machine. He reached the end zone 119 times (a school record), running for 50 and throwing for 69.

Flacco has been one of the most durable quarterbacks in the NFL, making 41 straight starts. The only time he was sidelined in the regular season was 2015, when he tore two knee ligaments and missed the final six games.

Despite injuring his hip on the opening drive against Pittsburgh, Flacco didn't miss a snap and said after the game that he wasn't affected by the injury. But he couldn't practice all week -- marking the first time that occurred in the regular season in his 11-year career. He is in the midst of another disappointing season, throwing for 12 touchdowns with six interceptions (84.2 passer rating) while struggling to pass the ball downfield.

This could be Flacco's final season in Baltimore. The Ravens can create $10.5 million in cap space by cutting him after the season or free $18.5 million in space by designating him as a post-June 1 cut.