J.D. Walton was placed on injured reserve Monday. He had started 38 consecutive games, including playoffs. (Andrew Mason)

As expected, Broncos center J.D. Walton was placed on injured reserve Monday after fracturing and dislocating his left ankle Sunday.

Walton suffered the injury when Oakland DE Jack Crawford inadvertently rolled up on him while tackling RB Lance Ball with 3:38 left in the second quarter Sunday. The severity of the injury was readily apparent; Oakland LB Rolando McClain and Broncos TE Jacob Tamme immediately signaled for medical personnel to treat Walton.

But amid a flurry of roster moves that include two players returning from suspension, the Broncos won't have to cut anyone -- not yet, anyway.

LB Joe Mays and TE Virgil Green were back at Broncos headquarters for the first time since serving their one- and four-game suspensions, respectively. Mays takes Walton's spot on the 53-man roster. But the length of Green's absence gives the Broncos a one-week grace period to decide whether he'll be on the 53-man roster or not.

The Broncos got up to 53 players prior to Walton's injury by promoting rookie S Duke Ihenacho and second-year LB Mike Mohamed from the practice squad Saturday. Both were active and played on special teams in the 37-6 win over Oakland.

Green can practice with the team this week. The Broncos waived Mohamed late Monday afternoon, so they would not need to make another corresponding move to place Green on the 53-man roster -- unless they sign someone else.

"(Green) is in very good shape, and he's had a lot of time to get in shape," Broncos coach John Fox said.

"He proved to us last year and in the amount of camp he was allowed to go through (in 2012) that he's a good blocking tight end, and he's got good pass-catching skills to go with that," Fox said.

Green gives the Broncos another option for a blocking TE behind Joel Dreessen. Second-year TE Julius Thomas is used to back up Tamme, since Thomas is more of a pass-catcher in space than Green.

"It's kind of an area where we've been holding our breath a little bit," Fox said. "We've been fortunate because Joel has been healthy and good, and that gives us another 'Y' tight end."

Koppen's turn:Ex-Patriots center Dan Koppen, who was signed Sept. 11 after being released at the final preseason cutdown, stepped in for Walton on Sunday, and the offense didn't miss a beat.

"He's got that experience, just like Peyton Manning has a lot of experience," Fox said. "When you get to a new offense, new teammates, under pressure, it takes a minute to get accustomed to it. It'll be the same for him as it's been for Peyton."

Koppen missed 15 games last season with an injury similar to Walton's after anchoring the Patriots' offensive line for eight seasons.

Passing wasn't the plan:Well, it was in the Broncos' general game plan, but not on the calamitous fake field-goal attempt late in the second quarter Sunday, when K Matt Prater threw a wildly optimistic pass to OL Zane Beadles. Predictably, the 305-pounder failed to come down with the football.

"It was actually designed to be a run," Fox said. "For the record, we weren't planning to throw a bomb to Zane Beadles."

The play began to disintegrate when Oakland LB Miles Burris worked past Broncos OL Orlando Franklin -- normally a right tackle who lines up on the left side on field goals. With Burris bearing down on him, Prater stopped, then threw.

"We probably could have done a better job of coaching it," Fox said.

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