The Oakland Raiders are set for a huge AFC West divisional matchup against the Kansas City Chiefs on Sunday afternoon with many implications involved.

The Raiders may have to take the field once again without star wide receiver Amari Cooper as Michael Gelken of the Las Vegas Review-Journal is reporting that he is still working his way through the concussion protocol.

A couple hurdles remain before Cooper can return to action. For one, he hasn’t formally cleared concussion protocol, a team official said Tuesday. He also continues to rehab an ankle injury, which is expected to be of greater impediment to his availability Sunday against the Kansas City Chiefs at Arrowhead Stadium.

It is a complicated situation surrounding Cooper, who is also dealing with an ankle injury that he suffered on the same play he suffered the concussion. In fact, the status of his ankle is deemed a more significant concern at this point.

Outside of his huge performance against the Chiefs in Week 7 where he hauled in 11 catches for 210 yards and a pair of touchdowns, Cooper has struggled to find any consistency. He has posted fewer than 65 yards in the other 10 games played this season while currently sitting at 42 catches for 499 receiving yards and five touchdowns.

If Cooper is unable to make his return on Sunday, the Raiders will likely lean more heavily upon wide receiver Michael Crabtree, who is returning from a one-game suspension stemming from his altercation against Denver Broncos cornerback Aqib Talib in Week 12. Tight end Jared Cook and wide receiver Seth Roberts could also factor more greatly into the equation in the passing game.