Broncos center Dan Koppen is out for the season after tearing his left ACL on Sunday in 9-on-7 drills less than six weeks after rejoining Denver following J.D. Walton's setback in his comeback from ankle surgery.

Koppen an 11-year veteran who played his first nine seasons with the Patriots was caught in a pile early in the workout and was carted off the field and taken for an MRI which revealed the season-ending injury.

Koppen's injury had earlier been reported by The Denver Post.

Manny Ramirez who took most of the snaps at center during Denver's offseason practices stepped in for Koppen whose teams have gone 108-28 in games he has started.

"I always cringe" a somber-sounding coach John Fox said after practice. "You never like to see players get injured particularly severely injured. But you understand when you do this long enough whether you're a player or a coach that this happens. You know you get them back ready. And you've got some guys that have worked hard off of injuries last year and it will be no different this year."

Koppen's injury is the latest setback to Peyton Manning's patched-up pocket of protection.

Left guard Zane Beadles was the only starting lineman to come out of last season unscathed.

All-Pro left tackle Ryan Clady has been limited at training camp since signing a $57.5 million contract earlier this month as he recovers from right shoulder surgery. Tackle Orlando Franklin (toe shoulder) and guard Chris Kuper (ankle) are also coming off surgeries. Franklin has been back at practice but Kuper hasn't.