Jeremy Maclin not participating in Thursday's practice

Eagles wide receiver Jeremy Maclin. (Matt Rourke/AP)

FOXBOROUGH, Mass. -- Jeremy Maclin is not participating in Thursday's practice with the New England Patriots, leaving his status in doubt for Friday's second preseason game.

Maclin wore a baseball cap and was not stretching with the team at the beginning of the practice, which is expected to include situational work. He was one of seven players without helmets: cornerbacks Nolan Carroll (hamstring) and Jaylen Watkins (hamstring); running backs Chris Polk (hamstring), Matthew Tucker (hamstring), and David Fluellen (undisclosed); and linebacker Jake Knott (hamstring).

Wide receiver Riley Cooper was wearing a helmet and stretching. He has not been a full participant this week.

The biggest name in the group is Maclin. He tweaked his hamstring in Wednesday's practice

"It shouldn't be a big deal," Maclin said after practice. "Go back, treat it, and come back tomorrow."

That did not appear to be the case.

If Maclin and Cooper are both out, then the Eagles would be missing their top two wide receivers. Coach Chip Kelly is not scheduled to address reporters after practice. Ifeanyi Momah, Jeff Maehl, and Arrelious Benn have all taken first-team snaps this week. Brad Smith remains the No. 1 slot receiver, although Jordan Matthews can push for time, too.

The injuries to the three running backs leaves the Eagles short on depth at that position. The only healthy running backs are LeSean McCoy, Darren Sproles, and Henry Josey. Look for Josey, an undrafted rookie from Missouri, to get a chunk of the carries.

Carroll's injury has lingered for more than a week, and he's likely to miss his second preseason game. Carroll was making a push to earn playing time before he was sideline. Watkins, the fourth-round pick, is also a player expected to factor onto the 53-man roster this season. 

More to come after practice.