The Kansas City Chiefs might be staring at another hurdle on the injury front before their upcoming clash against the Denver Broncos. Rookie Mason Thomas was notably absent from Thursday’s practice, sparking worries about his availability for Monday’s (September 14) game.

“DE R Mason Thomas did not practice Thursday. Chiefs report he was out with a hamstring issue. He was wearing a compression sleeve on his right leg,” Matt Derrick posted on X.

The Chiefs wrapped up their second practice of the week on Thursday, September 3, and now they’re getting a bit of a breather. Three days off before a single practice session next Monday or Tuesday, then it’s back to a regular schedule starting Thursday, September 10.

It’s the first time R Mason Thomas has shown up on the injury report since training camp kicked off back in late July. However, Thomas has missed multiple games in three of his four years in college at the University of Oklahoma, dealing with both ankle and quad issues.

Despite that, he put up a solid resume, finishing with 25.5 tackles for loss and 17 sacks. He missed three games in both 2022 and 2025. None of those past injuries scream long-term trouble, but the pattern of missed time is something worth keeping an eye on.

About the hamstring, he is dealing with a typical grade 1 strain that usually takes somewhere between one and three weeks to heal in the NFL. With eleven days left before Kansas City opens the season against Denver, there’s a slight chance Thomas gets back on the practice field and suits up for that game. In fact, a source told Bob Fescoe that the Chiefs expect him back once practice resumes next week.

Still, until we actually see him out there, it’s hard to know just how serious this is. Whether he’s a full go, working in a limited capacity, or held out entirely will say a lot about how the team handles the next couple of weeks.

If Thomas can’t go, the Chiefs’ edge rusher depth gets shaky fast. Ashton Gillotte’s Week 1 status is up in the air too, who has been out with a ruptured plantar fascia.

Jack Pyburn just got claimed off waivers and is still catching up. That would leave George Karlaftis and Felix Anudike Uzomah as the only healthy options on the 53-man roster. Worth remembering that practice squad defensive end Tyreke Smith was also nursing a hamstring injury before roster cuts came down. Emmanuel Ogbah is another name who could get the call-up for added depth if needed.

Both Gillotte and Thomas were at practice Thursday but didn’t participate, and Chamarri Conner was in the same boat. Tyreke Smith was also seen without a helmet. Conner’s nursing a knee injury, and Thomas is the newest addition to that list.

Put it all together, and it’s a lot for a team that’s already watching its franchise quarterback work his way back from injury.

Chiefs dealing with injuries across the roster

Kansas City’s injury report heading into Sunday is stacked. Patrick Mahomes tops the questionable list with a knee issue, and he’s got plenty of company there too. Trey Smith is nursing a hip problem, L’Jarius Sneed a knee, Drue Tranquill and Alohi Gilman are both dealing with back issues, and Josh Simmons has a back concern of his own.

Then there’s the IR list, and it’s not short either. John Michael Gyllenborg, EJ Smith, Jeff Caldwell, Jimmy Holiday, Ethan Downs, C.J. Hanson, Chris Oladokun, and Matt Waletzko are all already ruled out, while Omarr Norman-Lott is still working his way back on PUP.

One name missing from that early update was Chris Jones, who sat out Wednesday with a back injury. Reid didn’t seem too worried about it, and is sure enough that Jones will be back soon. Not everyone bounced back, though. Josh Simmons and practice squad lineman Marcus Harris were both absent, per KC Star’s Sam McDowell.

There was better news on the Trey Smith front. He’s ready to go for the season opener.

“Yeah, yeah, absolutely,” he said when asked about his chances in Week 1.

And when questioned about what actually caused the hip injury in the first place, he brushed it off.

“Nothing, man. You know, I mean, we’re just getting after it. We’ll be back. It’s no problem. Yeah, so far, it’s football. You never feel 100%.”

Sounds like the hip might just be something he plays through all year. Either way, with this many players nursing injuries, Kansas City’s depth is about to be tested heading into the battle against Denver at Arrowhead.