Case Keenum will start for the Browns in place of Baker Mayfield, who’s played through a shoulder injury.

CLEVELAND • Baker Mayfield had to surrender to the pain.

Cleveland’s starting quarterback, who has played the past four weeks with a torn labrum in his left shoulder, will sit out Thursday’s game against the Denver Broncos and backup Case Keenum will start.

“I feel very ready. I’ve been ready,” said Keenum, who hasn’t started since 2019 with Washington. “You can say, ‘ You don’t have to get ready if you stay ready’ and I’ve been ready since I got here.”

The Browns (3-3) announced the switch on Wednesday, ending speculation about whether Mayfield would try to push through an injury to his non-throwing shoulder that he suffered last month and has worsened in recent weeks.

“Case Keenum will be our starter tomorrow night and we have full confidence in him to lead us and do the things necessary to put us in position to win,” Browns coach Kevin Stefanski said. “Baker fought really hard to play, he’s a competitor and obviously wants to be out there but just couldn’t make it on a short week.

“We know he will continue to do everything in his power to return as quickly as possible.”

Mayfield was limited in practice on Tuesday, when he said he still expected to play. However, with this being a short week, there wasn’t enough time for the swelling in his shoulder to go down and it was decided early Wednesday for him to rest, ending Mayfield’s streak of 53 consecutive starts for Cleveland.

The loss of him means the Browns’ entire starting backfield has been wiped out by injuries.

Nick Chubb and Kareem Hunt, the NFL’s top running back tandem, will sit out with calf injuries. Cleveland could also be missing star receiver Odell Beckham Jr. due to a shoulder injury, and starting offensive tackles Jack Conklin (knee) and Jedrick Wills Jr. (ankle) haven’t practiced this week and could be game-time decisions.

“It’s always a great challenge,” Keenum said when asked about missing key players. “That’s what this league is about. Nobody’s at 100%. After Week 1, nobody’s playing at 100%. That’s the way it goes. That’s the hard truth, that’s why it’s a grown man’s league.”

On Tuesday, Mayfield was still planning to play despite a shoulder tear that was affecting his play and sleep. The 26-year-old underwent an MRI on Monday and the results were examined by a shoulder specialist, Dr. Orr Limpisvasti, the team physician for the NHL’s Anaheim Ducks, who agreed Mayfield should rest.

Mayfield needs the swelling in his shoulder to go down first before he can strengthen the injured area. By sitting out against the Broncos (3-3), Mayfield will have some extra time because the Browns don’t play again until Oct. 31 against Pittsburgh.

The 2017 Heisman Trophy winner hasn’t missed a game due to injury since 2013 when he was a walk-on at Texas Tech.

“He is a tough, tough, tough, tough dude,” Keenum said on a Zoom call. “He fought through some serious pain just to practice and just to get going a little bit. ... It’d take a freight train to keep him out of the game, and I’m assuming that’s what it did because that dude plays through some serious pain.

“It’s impressive to be around. It’s inspiring. I know the guys feel the same way.”

Mayfield has been wearing a harness to stabilize his shoulder since getting hurt on Sept. 19 while trying to make a tackle against Houston after he threw an interception. He said Tuesday that the pain in his shoulder had increased after it twice popped out in Sunday’s loss to Arizona.