Carolina Panthers quarterback Sam Darnold is day-to-day with a shoulder injury after having undergone an MRI, according to NFL Network's Ian Rapoport.

His availability for Sunday's matchup with the Arizona Cardinals remains up in the air.

The 24-year-old was forced to exit the Week 8 game against the Atlanta Falcons in the fourth quarter after taking a hit to the head. He was ruled out due to a concussion.

Prior to leaving the game, Darnold completed 13-of-24 passes for 129 yards and added 66 rushing yards on eight carries.

The USC product was replaced by backup quarterback P.J. Walker, who nearly threw an interception on his lone pass attempt. Chuba Hubbard punched in a six-yard touchdown to close out the drive as the Panthers went on to win, 19-13.

Carolina acquired Darnold from the New York Jets during the offseason. Through nine games, he has 1,986 passing yards, seven touchdowns and 11 interceptions.

He helped lead the Panthers to a 3-0 start to this season, but he's cooled down considerably as they are 1-4 in their last five games. He had a stretch of four straight games with an interception and was benched in the Week 7 loss to the New York Giants.

In the wake of Darnold's erratic play, the Panthers were linked with a trade for Houston Texans quarterback Deshaun Watson. However, Carolina head coach Matt Rhule publicly voiced his confidence in the former Jets player.

"He just needs a lot of help from a lot of guys right now that he's not getting," he said after Darnold's benching in Week 7. "But I see all the good moments too. I see the good things. We're going to keep coaching him. ... Obviously, I want Sam to play better. But he's the guy."

Drafted third overall by the Jets in 2018, Darnold did not perform up to expectations in New York. In his three seasons there, he was 13-25 in 38 career starts. Turnovers have been an issue throughout his career, as he entered this season with 39 career interceptions and nine fumbles lost.

Without Darnold, the Panthers will turn to Walker as he's the only other quarterback currently on the roster. He was Temple's starter when Rhule coached the team from 2013-16. He was signed by the Indianapolis Colts as an undrafted free agent in 2017 but failed to make the team.

The 26-year-old spent time in the XFL with the Houston Roughnecks in 2020, leading the league in both passing touchdowns and passing yards before it suspended operations due to the COVID-19 pandemic.

Walker signed a two-year contract with Carolina prior to the 2020 season. He made three appearances in 2020 with one start and threw for 368 yards with one touchdown and five interceptions.