Von Miller could miss the entire 2020 NFL season with an ankle injury, according to reports.
NFL Network and ESPN both reported Miller had an MRI after suffering an injury in practice on Tuesday, and the initial diagnosis suggests the eight-time Pro Bowler has injured a tendon that will require season-ending surgery.
Miller is thought to be seeking a second opinion on Thursday before determining whether he needs to go under the knife.
The Broncos, who have not confirmed the news, tweeted a picture of Miller with a praying hands emoji.
Miller, 31, is one of the NFL's elite edge rushers and has 106 sacks since entering the league in 2011 - 10 more than any player in that span.
In 2018 he formed one of the best pass-rushing duos in the league with rookie Bradley Chubb - the two combining for 26.5 sacks - but Chubb only played in four games last year due to injury.
Super Bowl 50 MVP Miller had eight sacks in 2019 - the first time he had failed to reach double digits since a suspension-hit 2013 - but there was optimism about a bounce-back campaign, both for him and the Drew Lock-led Broncos.
However, Denver have potentially suffered a crushing blow on the eve of the new season, with less than a week to go before they face the Tennessee Titans in Week 1.
Houston Texans defensive end JJ Watt, who has suffered his own injury issues in recent years and was drafted nine picks after Miller in 2011, tweeted: "Absolutely hate to hear the news @VonMiller, the game is better when you're out there. Know you'll dominate the recovery and come back swinging."
Team-mate Chubb, Seattle Seahawks quarterback Russell Wilson and Los Angeles Chargers defensive back Chris Harris - who used to play in Denver - were among the others to offer well wishes to Miller on Twitter.Published 09 Sep 2020, 13:06 IST