CHARLOTTE, N.C. -- Quarterback Baker Mayfield will return to the starting lineup for the Carolina Panthers on Sunday after an MRI taken over the weekend revealed that PJ Walker suffered a high ankle sprain in Thursday night's victory over the Atlanta Falcons.

Sam Darnold, who lost the open competition to Mayfield for the starting job during training camp, will be the backup for the Week 11 game against the Baltimore Ravens.

This will be Mayfield's first start since he suffered an ankle sprain in a Week 5 loss to the San Francisco 49ers. He was replaced by Walker the next week against the Los Angeles Rams and had remained the backup the past four games despite being healthy enough to play.

Mayfield's only playing time the past month came in the second half of a 35-17 blowout loss at the Cincinnati Bengals in Week 7 in which he led three scoring drives, going 14-for-20 passing for 155 yards and two touchdowns.

Mayfield struggled to a 15.3 Total QBR during a 1-4 start that was the lowest in the NFL this season and the worst since ESPN began using the statistic in 2006. He had four interceptions and four touchdown passes during that stretch.

Interim coach Steve Wilks said the No. 1 thing Mayfield has to do against the Ravens is "protect the football.''

Having a solid running game led by D'Onta Foreman should take some pressure off Mayfield, who was the top overall pick of the 2018 NFL draft. The Panthers rushed for a season-high 232 yards against Atlanta and have averaged 159.5 yards rushing the past four games since trading star back Christian McCaffrey to the San Francisco 49ers. They averaged 89.9 yards rushing the first give games with Mayfield starting.

"Everything starts up front,'' said Wilks, who has committed to the running game since Matt Rhule was fired after a 1-4 start. "We've got to do a great job of really establishing the run game, and when we do pass, we've got to do a great job of giving him a clean pocket so he can go through his progressions and get the ball down the field.''

With Darnold returning last week from injured reserve and Walker playing well, the Panthers had been looking at all options at quarterback, including a possible release of Mayfield, according to a league source.

Walker was 2-3 as the starter, including Thursday night's 25-15 victory over the Falcons that kept Carolina (3-7) a factor in the NFC South, which is led by the Tampa Bay Buccaneers (5-5). He suffered the injury in the fourth quarter, but it never was reported because, as Wilks said, Walker "sucked it up and played through it.''

Wilks put no timetable on the injury, saying only that Walker would not go on injured reserve.

"A high ankle sprain limits his mobility ... so we'll let him sit this week and go with Baker,'' Wilks said.

Mayfield has plenty of experience facing the Ravens after spending his first four NFL seasons with the Cleveland Browns in the AFC North before being traded to Carolina in July.

In his eight starts against Baltimore, the Browns went 3-5 as he posted an 83.2 passer rating while throwing 13 touchdown passes and nine interceptions.