A person familiar with the injury to Dumervil told The Associated Press on Thursday that the reigning NFL sacks king could be sidelined for up to five months, making it difficult for Dumervil to return this season. The person spoke on the condition of anonymity.
Coach Josh McDaniels said the team is evaluating courses of treatment for the pass-rusher and there is no timetable for his return. Surgery hasn't been ruled out, either.
Dumervil was hurt at practice Wednesday night in a one-on-one passing drill, and walked off the field clutching his right arm. The Broncos described the injury as to the "pectoral area of his chest."
ESPN NFL Insider Adam Schefter was the first to report the injury.
The 26-year-old Dumervil led the league with 17 sacks in 2009 and parlayed his breakout season into a five-year, $58.332 million extension last month that included $43.168 million in guarantees against injury, a record for a player at his position.
"Nobody is going to replace him as an individual. We know that," McDaniels said. "We're not going to try to do that."
Without Dumervil, the Broncos lack a bona fide pass-rusher. Defensive lineman Darrell Reid had four sacks last year, the most of any other returning Broncos player. But he's sidelined with a knee ailment and hasn't participated in training camp.
The other outside linebackers, former first-round picks Robert Ayers and Jarvis Moss, didn't have a sack last year. Mario Haggan played on the other side of Dumervil in '09, but was moved into the middle during training camp. He may just be moved back to the outside in light of Dumervil's injury.
"Elvis wouldn't want us to bow our heads and think it's the end of the world," Ayers said. "That's not what we're going to do. ... We've got to keep the show going."
The Broncos will stick to their 3-4 scheme but are considering sprinkling in some of their old 4-3 alignments.
McDaniels beefed up his defensive line through free agency in the offseason and the centerpiece of that project, nose tackle Jamal Williams, practiced Thursday for the first time since camp started.
The 348-pound Williams, who spent his first 12 seasons with division rival San Diego, was brought in to be a run-stuffer and help push the pocket, allowing players such as Dumervil to apply more pressure to the quarterback.
"We're not going to change the style of defense that we have. There might be a bigger body out on the edge sometimes," McDaniels said. "It may take a few people, may take some creativity for us."
Training camp has certainly gotten off to a bad start for the Broncos.
The Broncos lost their top two tailbacks, Correll Buckhalter (back) and Knowshon Moreno (hamstring), on the first day of camp. Moreno is expected to miss the rest of camp, and Buckhalter is expected back next week.
Denver was already without All-Pro left tackle Ryan Clady as he recovers from a torn left patellar tendon he suffered playing basketball in the offseason.
All these standouts going down reminds McDaniels of the 2008 season when he was the offensive coordinator in New England and Tom Brady was lost for the season with a knee injury in the opener.
"Anytime you lose a player for a period of time that has that kind of impact on your team, nobody looks forward to that," McDaniels said. "But they're not going to write at the end of the season, 'Our record was such and such and Elvis Dumervil had an injury in training camp.' They're just going to tell you what our record was.
"We're not going to sit here and feel sorry for ourselves."
Just when the Broncos received backfield reinforcement with the signing of free agent and Denver native LenDale White on Wednesday, their All-Pro outside linebacker got hurt.
Dumervil prospered last season in the Broncos' new defensive look that converted him from a classic 4-3 defensive end into a stand-up outside linebacker in the 3-4, which employs three down linemen and four linebackers.
Despite his diminutive stature -- 5-foot-11 and 248 pounds -- Dumervil's extraordinarily long arms and low center of gravity make him difficult to defend as he has built-in leverage against almost anybody he faces.
He has 43 sacks since being drafted in the fourth round out of the University of Louisville in 2006.
Dumervil was anticipating another big season, too, joking around before camp began about the pressures of trying to defend his sacks crown.
"We all feel bad, obviously, for Elvis," McDaniels said. "I know how badly he wanted to start the season."
Adam Schefter is ESPN's NFL Insider. Information from The Associated Press was used in this report.