An obstacle on the left before full clearance

Kansas City Chiefs quarterback Patrick Mahomes was on the training ground and worked with the starting attack on a limited basis Thursday, but remains in concussion protocol.

Head coach Andy Reid clarified that Mahomes is still in the non-contact phase of the concussion protocol until further notice, leaving the Chiefs’ quarterback situation unstable for the AFC championship game on Sunday.

As a rule, players who have not been cleared of the NFL concussion protocol are not permitted to wear a helmet during practice. In Thursday’s practice portion open to media, Mahomes held on his helmet and watched from the sidelines.

But later in practice, Mahomes donned a helmet and played with the starting attack, which featured rookie back Clyde Edwards-Helaire. Edwards-Helaire missed the divisional playoff game last week with hip and ankle injuries.

“Pat looked good over there,” said Reid. “He moves well. He feels good. It’s just important that we follow protocol, and that’s what we do.

If Mahomes does not receive full medical clearance, Reid said the Chiefs will return to Chad Henne. Henne entered last week’s game in the third quarter after Mahomes was helped off the field at the end of a running option game. Henne also started week 17 with key staff resting from chefs.

Wide receiver Sammy Watkins (calf) and cornerback Bashaud Breeland (concussion protocol) were also on the training ground Thursday.

Running back Le’Veon Bell (knee) and cornerback Willie Gay (ankle) did not practice, Reid said.