​The Kansas City Chiefs will be without rookie defensive lineman Ethan Downs in 2026 after the former Oklahoma Sooners standout sustained a serious left knee injury at training camp in St. Joseph, Missouri. Downs signed with Kansas City as an undrafted free agent earlier this year and was considered a dark-horse candidate to make the Chiefs’ 53-man roster in a dual role as a pass rusher and special teams contributor. Veteran beat writer Matt Derrick of Chiefs Digest was among the first reporters to break the news of Downs’ disappointing injury in a post to Twitter on July 28, just days after Kansas City’s rookies reported to training camp:Chiefs DE Ethan Downs torn the ACL in his left knee, per source. Downs was a strong candidate to make the roster as depth at edge rusher as well as a multiple phase special teams player. He and R Mason Thomas were teammates at Oklahoma.— Matt Derrick (@mattderrick) July 28, 2026Derrick’s report indicated that Downs tore the ACL in his left knee and noted that the rookie pass-rusher was a college teammate of R Mason Thomas, who was selected by the Chiefs in the second round of the 2026 NFL Draft. This article originally appeared on Chiefs Wire: Chiefs lose top rookie to season-ending knee injury at training camp