Broncos coach Vic Fangio confirmed that Chubb, the fifth overall pick in the 2018 draft, suffered the season-ending injury in Denver's 26-24 loss Sunday to the Jacksonville Jaguars.
"It's a huge loss," Fangio said Monday. "He's one of our better players, obviously. He's a tempo-setter, a great person, a great leader."
Fangio said Chubb had discomfort in his knee Monday morning and was sent for an MRI, which revealed the partial tear. The star outside linebacker left Sunday's game twice -- first for a calf injury, then for the knee injury -- before returning to the lineup to close out the contest.
"He felt good enough to come back in, and actually he played that last series pretty damn well," Fangio said. "[He] had some really good pass rushes, caused that fumble that [we] weren't able to get. So he was as surprised, I think, as anybody this morning when he woke up feeling the way he did."
Chubb suffered the injury with just over 14 minutes remaining when he was engaged with Jaguars tight end Geoff Swaim on a run by running back Ryquell Armstead. In all, he played 74 of the team's 85 snaps on defense, including all of the snaps on the Jaguars' game-winning drive in the closing minutes.
Fangio said the Broncos will have to consider their options to fill Chubb's large presence in the defense as well as his roster spot. Rookies Malik Reed and Justin Hollins could be part of the equation, but the Broncos will likely have to add a linebacker.
Veteran outside linebacker Dekoda Watson, who was with the Broncos during the preseason, is currently a free agent and is another possibility.
In terms of recovery, Chubb won't have to look far for advice. Von Miller tore his ACL in December of the 2013 season and had at least 10 sacks in each of the next five seasons entering this year.