Head coach Mike Shanahan delivered the bad news as the first item of this afternoon's press conference: rookie safety Phillip Thomas was done for the year with a torn Lisfranc ligament.
This very painful injury occurs when one or more of the metatarsal bones are displaced from the tarsus in the middle of the foot.
Injuries like this are most typical in major impact situations (car accidents, industrial accidents) and are unusual, but not unheard of in football.
Shanahan initially reported that a Lisfranc injury was unlikely, but a second round of tests today yielded conclusive results.
"The X-rays at first were negative. They took an MRI, saw a little light spot on the MRI. Dr. [Robert] Anderson wanted to take a look at it," Shanahan explained. "When the swelling went down, they took another X-ray and they found that Lisfranc ligament needed an operation.
"That's what we're going to have and it'll be about four- or five-month recovery time. We'll put him on IR."
This is a big blow to a secondary that spent three picks in the 2013 NFL Draft on defensive backs. The trio started the preseason opener in Tennessee and drew praise from Shanahan, who predicted a bright future.
"You get a feel very quickly of guys that have a chance to play. All three guys, you could see, have football instincts," he said. "It will be fun to put them in game situations, but they've been able to handle everything thus far.
"It's kind of a fun process to watch the guys develop – How do they grow? Do they keep maturing?"
For Thomas, that question will have to be answered in 2014 and beyond.
While Lisfranc injuries are painful and unusual in nature, it is not unprecedented for players to return to an elite level after surgery and recovery.
Other NFL players that returned to form after surgery include Santonio Holmes, Maurice Jones-Drew, DeMarco Murray, Matt Schaub and fellow rookie teammate Brandon Jenkins.
Jenkins will serve as a valuable resource to Thomas during his recovery process.
Prior to injury, he was listed as the team's third strong safety, but had a chance to contribute early with Brandon Meriweather returning from ACL reconstructive surgery and Reed Doughty playing a key role on special teams.
Although they were likley competing for different positions and playing time, the decision to draft Bacarri Rambo in the sixth round after taking Thomas now looms even larger for Shanahan and the defensive coaching staff.
Removing Thomas from the safety competition still leaves the team with a host of options, with Meriweather, Doughty, Rambo, DeJon Gomes, Jordan Pugh and Jose Gumbs still on the roster.
Shanahan did not rule out looking elsewhere for talent, but suggested that the team would likely replace Thomas from within the organization.
"We will just wait and see. We got 90 players in camp. You lose a guy, competition still goes on," Shanahan said. "These guys are one play away from being the starter. We've got a lot of quality players out there.
"It will be interesting to see who makes the final 53 and also the eight on the practice squad."