The full severity of the injury will be determined by further examinations today, with the Chiefs unsure whether Moeaki will make a swift return or be ruled out for the majority of the season.
The 26-year-old has had a torrid time with injuries during his career, and this latest one could threaten his position on the Chiefs' roster with final cuts due on Saturday.
However, coach Andy Reid is hopeful that this will be his last injury and that he can go about forging a successful career once he returns.
"He's had a couple of injuries, but I think some of those, in a lot of cases, with different players, sometimes you can change that around in your career," Reid told The AP.
"Hopefully this is his last one and he'll be able to keep going."
The Chiefs will play their final warm-up match against the Green Bay Packers on Thursday before beginning their regular season at the Jacksonville Jaguars on September 8.