Foxborough, Mass. — New England Patriots quarterback Mac Jones missed Thursday’s practice with an illness, according to the team.

Jones was the only player on the Patriots’ 53-man roster not spotted during the media-access portion of practice. Jones was a full participant in Wednesday’s padded practice after recovering from the back spasms he suffered last Sunday at Miami.

It’s unknown how long he will be absent with his new illness.

According to multiple reports, Jones’ sickness is not believed to be COVID-related. The young quarterback “had an upset stomach” and was given the day off, per the NFL Network. Thursday marked the first missed practice of his career.

On Wednesday, Jones declared himself fit to play against the Pittsburgh Steelers this weekend.

“Everything feels good,” he said, when asked about his back.

Veteran backup Brian Hoyer led the first-team offense in Thursday’s practice, while fourth-round rookie Bailey Zappe directed the scout team. The Patriots typically run through the third-down portion of their game plan on Thursdays. On Wednesday, Jones and the offense executed the first and second-down plays they want to execute in Pittsburgh.

Friday practices are typically light and always non-padded.

Linebacker Ja’Whaun Bentley, who missed Wednesday’s practice with a hurt toe, appeared to move without limitation during warmups on Thursday. On the field, the Patriots were down practice-squad linebacker Cameron McGrone, defensive lineman LaBryan Ray and offensive lineman Bill Murray. McGrone and Ray were also absent Wednesday.