Broncos' Dan Koppen tears ACL
Koppen, an 11-year veteran, was caught in a pile early in the workout and was carted off the field and taken for medical tests.
He had been re-signed by the Broncos last month to address the center position after starter J.D. Walton's had ankle surgery.
Manny Ramirez has worked at center for the Broncos this offseason before Koppen re-signed and presumably will return to the top of the depth chart at center.
"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."
Ramirez started 11 games at right guard last season.
"We need that flexibility," Fox said. "When you pick your offensive line, not just for the season, but for game day, you have to pick them from the standpoint of having some flexibility. You've got to have a swing guard/center, you've got to have a swing tackle/guard, for the games."
Walton is expected to be sidelined until the middle of October, however, The Post reported last month that Walton could miss the entire 2013 season if he suffers any complications in his rehab from the surgery, which was done to replace hardware inserted into his ankle during a surgery to repair an injury he suffered last year.
Walton's season ended on Oct. 1 last season when the Broncos placed him on injured reserve with a broken and dislocated left ankle. Koppen replaced Walton in the starting lineup last season.
Koppen, 33, was released by the New England Patriots before last season after 10 seasons with the team. He started 12 games for the Broncos after signing with the team.