JACKSONVILLE – The Jaguars' wide receiver position is thin again.

Perhaps most concerning, one of the reasons it's thin is a hamstring injury sustained by rookie wide receiver Allen Robinson this week in Jaguars 2014 Training Camp.

Robinson, a second-round selection in the 2014 NFL Draft, is expected to miss "extended time" – at least two weeks – after leaving practice Thursday with the hamstring issue. Robinson was one of four players the Jaguars announced Friday will miss extended time.

Wide receiver Tandon Doss (ankle), linebacker John Lotulelei (knee) and defensive tackle Jordan Miller (knee) also will be out at least two weeks, the team announced.

"Guys will step up," Bradley said late Friday morning after the Jaguars worked for about an hour and 35 minutes in 83-degree temperatures at the Florida Blue Health and Wellness Practice Fields.

"Ideally, you're looking to make sure that at Game 1 you're at good health. That's what we're looking at. Fortunately some of the injuries we have we're saying, 'They'll be back.'''

Bradley said he and General Manager David Caldwell will discuss on Friday afternoon the idea of adding to the receiver position.

"Well see with the extent of some of these guys," Bradley said. "It didn't affect us today. We worked tight red zone, so it had no effect on that. We might need an additional body."

Rookie guard Brandon Linder (foot) is listed as day-to-day and did not practice Friday. He had been working with the first team at right guard, and Jacques McClendon worked there Friday in his absence.

The Jaguars on Friday went through a shorter-than-normal practice, with multiple players including defensive end Tyson Alualu, running back Toby Gerhart, cornerback Dwayne Gratz, wide receiver Marqise Lee, offensive tackle Austin Pasztor, safety Johnathan Cyprien getting non-injury days off.

"I think we knew coming into training camp somewhere in the point of practice we were going to keep a good eye on our players to see where they were at," Bradley said. "We didn't know where. We didn't schedule it and say, 'Practice No. 7.' But we need them to understand they can trust us. They go out and practice and practice and practice and they need to trust us that when it's time we'll slow the tempo down. I think we wanted to take advantage of that."

Bradley also said Friday's practice, which featured a smaller amount of team drills than earlier workouts, was designed to "take the craziness out of the game."

"Right now, we're at the seventh install," Bradley said. "A lot of things are in their head. We wanted to come out here, slow it down and correct some things."

The injuries to Doss and Robinson leave the Jaguars' receiver position thin, with fourth-year veteran Cecil Shorts III already likely out at least four weeks with a hamstring injury and second-year veteran Ace Sanders out of camp dealing with personal issues.

The Jaguars had up to seven wide receivers out during offseason on-field work.

Robinson, who had been working with the starters in camp, was among the wide receivers who missed much of the offseason. He participated in a rookie camp in mid-May and a week of organized team activities, but was out with a hamstring thereafter. The hamstring injury he sustained Thursday is to the same hamstring, but a different muscle group.

"You'd love to have him, but it's one of those things where we're going to get him back," Bradley said.

Cornerback Alan Ball remained on the Physically Unable to Perform list, and the team announced he could be removed from the list next week.

The Jaguars will hold a walkthrough practice later Friday afternoon and will hold a mock game/scrimmage scheduled at EverBank Field Saturday at 6:45 p.m.

Poz jumped at the ? about Dakoda Watson. Really excited to see him. Loves his size & athleticism thinks he fits description of an OTTO LB — Brian Sexton (@JagsVoice) August 1, 2014

INJURY WATCH

Ball (ankle) and linebacker Dekoda Watson (sports hernia) remain on the Physically Unable to Perform list, with cornerback Aaron Colvin (knee) remaining on the non-football injury list. Safety Josh Evans (foot) practiced on a limited basis Wednesday and Shorts, Harbor, linebacker J.T. Thomas (hamstring), Lotulelei, Miller, Doss, Linder and Robinson out.

Jaguars WR Allen Robinson (hamstring), WR Tandon Doss (ankle), DL Jordan Miller (knee), LB John Lotulelei (knee) all out extended period. — John Oehser (@JohnOehser) August 1, 2014

PLAY OF THE DAY

The Jaguars held a shorter practice with limited team time Friday, but Hurns – getting added repetitions with injuries at the receiver position – caught a touchdown in the corner of the end zone on a perfect pass from Chad Henne. The play came in red-zone passing drills, and Hurns caught another touchdown on the other side of the field several plays later.

Henne to @a1hurns. #JagsCamp https://t.co/TRRTVrKBVq — Jacksonville Jaguars (@Jaguars) August 1, 2014

HIGHLIGHTS

*Linebacker LaRoy Reynolds, in coverage on Marcel Jensen, defensed a pass in the corner of the end zone, preventing a touchdown in goal-line passing drills. …

*Safety Chris Prosinksi had a pass breakup in red-zone passing drills late in practice.