Running back Jamaal Charles had exploratory surgery on his right knee Wednesday as the Chiefs try to determine why there is lingering pain from reconstructive surgery last season.
The surgery was performed by Dr. James Andrews, who has repaired both of his torn ACLs.
Charles was placed on injured reserve, which means he will miss at least eight weeks. The four-time Pro Bowl running back could conceivably return for the playoffs, but that appears to be a longshot.
Charles tore his right ACL in Week 5 last season. The Chiefs hoped he would be ready this season, but a series of setbacks limited him to 12 carries over three games
The Chiefs are also likely to be without Spencer Ware for Sunday's game against Jacksonville. He had not passed the league's concussion protocol after getting hurt last weekend in Indianapolis.
Copyright 2016 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.