BEREA, Ohio — Cleveland Browns starting center Nick Harris is out for the season after being placed on injured reserve Tuesday along with one of his backups, rookie Dawson Deaton.

Harris suffered a serious right knee injury on the second play of last week's exhibition opener at Jacksonville. The 23-year-old was dropping back to block for quarterback Deshaun Watson when his knee gave out and he crumpled to the grass.

Browns coach Kevin Stefanski did not provide any specifics on Harris' injury, and the team has not disclosed whether he's undergone surgery. Harris was seeking a second opinion before opting for an operation.

A fifth-round pick in 2020, Harris had been slotted to replace JC Tretter as Cleveland's first-team center this season. With Harris out, the Browns have moved Ethan Pocic into the starting spot, but might not be done addressing the key position.

Cleveland's interior depth took another hit Monday when Deaton, a seventh-round pick from Texas Tech, tore his anterior cruciate ligament. Stefanski did not say how Deaton got injured.

Also, All-Pro defensive end Myles Garrett missed his third practice after he was excused to attend to a personal matter.