Marvin Mims Jr. threw his helmet in frustration.

The Broncos wide receiver got injured on the opening series Friday in a 34-6 preseason win over the Vikings at Empower Field at Mile High. Quarterback Jarrett Stidham targeted Mims on a deep ball down the sideline. He fell awkwardly on the incompletion and looked in obvious pain.

Mims waved off athletic trainers and jogged to the opposite sideline under his own power. But Mims tossed his helmet at the Denver bench as he entered the blue medical tent. He left for the locker room. The Broncos announced Mims was questionable with a foot injury, and he did not return.

“With Mims, he’s going to be fine,” coach Sean Payton said. “It’s a bruise. So, we were really more just cautious with him.”

It’s been a challenging few weeks for Mims.

The fourth-year NFL wide receiver and return specialist suffered a muscle strain early in training camp. He’s been a mostly limited practice participant. Mims returned to full health for his preseason debut Friday against Minnesota. Positive vibes were short-lived.

Mims has time to heal before the Broncos open their season on “Monday Night Football” on Sept. 14 against the Chiefs. But it’s unclear how he will fit in a suddenly crowded position group.

There is little debate that Courtland Sutton and Jaylen Waddle are the Broncos’ two best wide receivers. The third option is still not solidified entering Week 1. The Broncos have several wide receivers — like Pat Bryant, Troy Franklin and Mims — with a chance to lock it down. Bryant and Franklin both had strong training camp performances.

“I’m a big fan of Marvin Mims,” Waddle said earlier this month in training camp. “He’s very explosive. I love watching him work. … Marvin is a big play always ready to happen. You’ve got to respect that type of speed.”

It seems more difficult to replace Mims as the team’s primary return specialist. The former second-round draft pick out of Oklahoma has been named twice to the Pro Bowl. On Friday, the Broncos offered a glimpse of who might replace Mims if health issues follow him into the regular season.

Wide receiver Kolbe Katsis, an undrafted rookie out of Northern Arizona, logged a 48-yard kickoff return against the Vikings. Katsis ranked fourth in the FCS last season with a kickoff return average of 30.6 yards. He’s flashed several times over the course of training camp and preseason.

The Broncos must cut down their roster to 53 players by 4 p.m. Sunday. They open the regular season on “Monday Night Football” on Sept. 14 against the Chiefs at Arrowhead Stadium.