ENGLEWOOD, Colo. (AP) — The winless Denver Broncos suffered the worst loss of their anguished season Monday when rising star Bradley Chubb was diagnosed with a torn left ACL that requires surgery and ends his season.

The fifth overall pick in the 2018 draft, Chubb was injured in the Broncos’ 26-24 loss to Jacksonville on Sunday although he finished the game and forced a fumble on the last series. The ball bounced right back to quarterback Gardner Minshew, who then drove the Jags for the game-winning field goal as time expired two weeks after the Bears had a walk-off field goal in Denver.

“He felt good enough to come back in and actually he played that last series pretty damn well, had some really good pass rushes, caused that fumble that we weren’t able to get,” coach Vic Fangio said. “So, he was as surprised, I think, as anybody this morning when he woke up feeling the way he did.”

In the postgame locker room, Chubb blamed cramps for his being on and off the field in the fourth quarter, although he was seen limping around the sideline and going into the medical tent.

“Just cramps,” Chubb said. “Feeling good now but need to shake that off, hydrate more and can’t let my team down not being on the field.”

Although Miller reached 100 sacks Sunday, it’s been Chubb who’s been rushing the passer more with Miller having more coverage and contain-the-edge responsibilities in Fangio’s defense. Chubb had one of Denver’s five sacks Sunday after the Broncos became the first NFL team to go the first three games without a sack or a takeaway.

“It’s a huge loss,” Fangio said. “He’s one of our better players, obviously. He’s a tempo setter, great player, great person, great leader, all that. So, it is a loss.”

Another gut-wrenching loss for the Broncos, whose 0-4 start matches their worst in history and stretches their overall losing streak to eight games. They face the AFC West rival Los Angeles Charges on Sunday.

“There’s no pity parties in the NFL, you know, we’ve just got to keep going,” said Fangio. “Those losses are our own doing. Injuries don’t have an effect on those. We’ve just got to keep going. But nobody’s feeling sorry for anybody here.”

In addition to trying to turn around their season without one of their best young players, the Broncos are left hoping Chubb bounces back as well as Miller did from his ACL injury in 2013 that sidelined him for Super Bowl 48.

Miller rebounded with a combined 25 sacks over the next two years and added five sacks in the playoffs after the 2015 season, including two strip sacks of Cam Newton in Super Bowl 50 that earned him game MVP honors and a huge contract extension the following summer.

With Chubb out, rookies Malik Reed and Justin Hollins are options to play opposite Miller at outside linebacker. Fangio said the Broncos also will look at outside help such as Dekoda Watson, whom the Broncos released this summer.