The injury is to the same shoulder Pacheco had surgery on this past offseason.
Asked whether Pacheco is a candidate for injured reserve, coach Andy Reid said Friday it was too early to tell.
Pacheco leads the Chiefs and is fifth in the NFL in rushing with 779 yards. He also has 33 receptions and seven total touchdowns.
He rushed for 110 yards and a touchdown in last week's game against the Green Bay Packers before being ejected in the fourth quarter for taking a swing at an opposing player.
Edwards-Helaire, the Chiefs' first-round draft pick in 2020, lost his starting spot to Pacheco last season and has played little in 2023, rushing for 140 yards and a touchdown. However, Edwards-Helaire will get the start Sunday, Reid said.
"[Edwards-Helaire] is going to be ready, no doubt," McKinnon said. "Everybody in that room is ready. When called upon, he knows what this moment means for him. So I'm 100%, 200% confident, and he's going to go out there and do his thing. He's prepped for it. He's looked good and the opportunities he's had this year ... he stayed focused and stays resilient and showing off. I expect to see nothing less on Sunday."
McKinnon missed the past two games because of a groin injury but will be available against the Bills. Playing mainly in passing situations this season, McKinnon has caught 19 passes with three touchdowns.