ST. JOSEPH, Mo. — Chiefs wide receiver Jeremy Maclin was held out of practice Monday after straining his neck the previous day, putting his availability for their preseason opener in question.

Kansas City visits Arizona on Saturday.

Chiefs coach Andy Reid said he was unsure when Maclin was hurt during Sunday's practice, or whether the injury occurred during a brief scuffle with cornerback Marcus Cooper.

Maclin had an X-ray Monday morning and spent practice working out with the trainers.

The Chiefs did get some positive injury news with the return of wide receiver Chris Conley to practice. The rookie has been out since the start of training camp with a knee injury.