Injuries force quarterback changes for NFL's Colts and Panthers
Richardson missed a third consecutive practice session while in the NFL's concussion protocols and will be replaced by backup Gardner Minshew on Sunday when the Colts (1-1) visit Baltimore (2-0).
Young, who suffered an ankle sprain in a Monday loss to New Orleans, will miss one or two weeks with the injury, Panthers coach Frank Reich said, with reserve Andy Dalton (35) stepping in to guide the Panthers (0-2) at Seattle (1-1).
"Bryce has done well this week," Reich said. "I'm optimistic that he's on the right path."
Despite Carolina's poor start, Reich said the starting job awaits Young when he is healthy no matter how well Dalton fills in for him.
"When he gets back and is cleared, he's our guy and he'll be ready to go," Reich said.
In his first two NFL contests, Young has completed 42 of 71 passes for 299 yards and two touchdowns with two interceptions. He has run five times for 51 yards but fumbled twice and been sacked six times.
Young was the top overall selection in this year's NFL Draft while Richardson was chosen fourth.
Dalton is in his 13th NFL season, including nine as a starter with Cincinnati and a starting role last year with New Orleans, where he went 6-8.
Reich called Dalton "starter worthy" and said he is "playing at a high level" from his work in practices.
Richardson ran for two touchdowns last week in a victory over Houston but reported a concussion in the second quarter after his head struck the turf and Minshew took over to secure the Colts' triumph, throwing for 171 yards and a touchdown.
Minshew, 27, is in his fifth NFL campaign and worked with Colts coach Shane Steichen the past two years as a backup in Philadelphia, where Steichen had served as offensive coordinator.
Richardson, 21, has completed 30 of 47 passes for 279 yards and a touchdown with an interception and run 13 times for 75 yards and three touchdowns while being sacked four times.
Burrow, who led the Bengals to the 2022 Super Bowl and last season's conference finals, remains questionable for Monday's game against the Los Angeles Rams due to a right calf injury.
Cincinnati signed quarterback Reid Sinnett to the practice squad, set for a backup role if Burrow cannot play and reserve Jake Browning (27) is pressed into a starting role.