At the end of nearly every training practice that there is what many refer to as an "opportunity" segment.

It's a time when the more established players, starters and stars are elsewhere on the field while young, less established players compete in 11-on-11 action.

Thursday morning at Gillette Stadium Bill Belichick's Patriots hit the field in full pads but the practice turned into extended opportunity reps for guys looking to fight their way up the depth chart.

While birthday boy Tom Brady, the healthy offensive starters and the top members of the secondary – a group that included 14 players -- departed midway through the session to the lower practice field normal reserved for rehab work, the remaining Patriots battled it out in group and team action for a shorter-than-normal workout.

Whether this was a pre-scheduled day of lighter work for the veterans or a reaction to some minor injury issues creeping up on offense is not clear.

New England has seen the receiver position, in particular, hit with issues that have limited Danny Amendola, Matthew Slater, Chris Hogan, Malcolm Mitchell and Cody Hollister in one form or fashion in recent days. The offense was also without left tackle Nate Solder and running backs Mike Gillislee and Brandon Bolden on Thursday.

Asked about dealing with injuries in camp during his pre-practice presser, Belichick's answer may have related to the way his practice unfolded shortly afterwards.

"Sometimes if a certain group is lower in numbers, that affects what either that side of the ball can do or maybe what the other side of the ball can do against it," Belichick explained. "Occasionally, we have to make some kind of modifications. Hopefully the train doesn't come to a complete halt and we're able to maybe do a little more of something else in order to manage the reps of a particular player or a particular group."

Even though the veteran players took it a bit easier on Thursday, here are one veteran reporter's full-effort Blogservations of the workout:

--Those players not seen on the field included Hollister, Matthew Slater and Solder. Hollister has been missing since he suffered an apparent left shoulder injury the second day of camp. Slater left practice early on Wednesday after an apparent leg injury. Solder practiced each of the first six days of camp and didn't appear to be dealing with a health issue during Wednesday's session.

--LB Dont'a Hightower and DT Alan Branch remain out of uniform and while on PUP continue to do rehab work on the lower field, as does rookie T Andrew Jelks, who is on NFI to open camp.

--Mitchell, David Jones, Duron Harmon, Gillislee, Hogan, James O'Shaughnessy and Bolden were dressed in full pads but retreated to the lower field for rehab work. Danny Amendola also did some rehab work for a time.

--Despite seemingly dealing with some sort of foot or lower leg issue late in practice on Wednesday, Julian Edelman did not appear limited in any way today.

--Kenny Chesney's "Boys of Fall" continues to be the song that's played during early practice stretching/form running.

--The defensive players worked on their tackling in early group work. Whether they were hitting large dummies or the big, rolling, donut-shaped pad, the players were taking the faux foe to the ground. Before the players actually did one drill with the donut pad, defensive line coach Brendan Daly demonstrated, diving to the ground for show.

--Some of the special teams coverage guys worked with Joe Judge on beating double-team blocks and flowing to the ball carrier.

--Brady was one of the first players on the field, flashing a huge smile on his 40th birthday. The crowd was filled with signs for TB12. Fans chanted for Brady during the time he was on the upper practice fields. After practice concluded the team came together in the middle of the field and the group turned to the side bleachers so fans could sing Happy Birthday to the G.O.A.T. Part of the training camp experience at Gillette Stadium on Thursday also included a small petting zoo area with five goats wearing Patriots jerseys in front of a large G.O.A.T. sign.

--Matt Lengel had a tough day. The veteran tight end had a couple real ugly drops, including one early throw from Brady as the tight ends worked on beating coverage on short throws. Special teams coach Bubba Ventrone served as the linebacker/safety in coverage for the tight ends in the drill.

--Wide receivers worked on their stalk blocking for a few minutes early in practice.

--The players that retreated to the lower field after the early practice group work included Brady, Rob Gronkowski, Edelman, Dwayne Allen, Brandin Cooks, James White, David Andrews, Joe Thuney, Shaq Mason, Marcus Cannon, Malcolm Butler, Stephon Gilmore, Patrick Chung and Devin McCourty.

--Early in opportunity team action, the entire second offense, including coaches, had to take a lap.

--While the skill players on offense did pretty low-key route running focused on the passing game while on the lower field the offensive lineman worked a bit harder. The four linemen had to push a weighted sled back and forth across the field one at a time. It's the same type of sled Steelers linebacker James Harrison was shown pushing on social media in recent weeks, though with much less weight on it.

--Former Patriots Sebastian Vollmer and Markus Kuhn watched the practice. The duo will be doing color commentary and play-by-play, respectively, in German of New England preseason games to be streamed back to Germany.

--Hogan wore a black sleeve on his right knee/lower leg, a day after seeming to twist the knee and later wearing ice it on the practice field on Wednesday.

--Shortly after the entire offense did a lap, the entire defense did the same thing, including all the coaches.

--Noteworthy that offensive coordinator Josh McDaniels went to the lower practice field with Brady and the rest. As such, wide receivers coach Chad O'Shea remained on the practice field wearing a headset and appeared to call the offensive plays. In the past, that fill-in role had gone to former tight ends coach Brian Daboll, who is now the offensive coordinator for Nick Saban at Alabama.

--On defense, Matt Patricia remained on the regular practice field wearing a headset and calling the plays.

--Jacoby Brissett connected with Devin Lucien on a pretty deep ball down the right sideline during the opportunity work, beating Dwayne Thomas.

--There were plenty of 1-on-1 reps on the upper field for both the linemen and skill players. D.J. Foster did a nice job beating Kyle Van Noy on a play from Jimmy Garoppolo. Brissett hit Rex Burkhead after he toasted Elandon Roberts.

--Kony Ealy had to take a penalty lap after a 1-on1 rep with the offensive linemen.

--Patriots owner Robert Kraft walked onto the field midway through the practice and watched the remainder of the session. Kraft had a long talk with Brady at one point and then left the field with his quarterback, walking down the stairs to Gillette Stadium after practice. Kraft also had an extended chat with Gronkowski at one point.

--Trevor Bates had tight coverage of James Develin in 1-on-1s and forced an incompletion.

Brady turns 40; Camp notes 8/3

--During a special teams/open field drill the ball carriers had to run toward and behind three large dummies before either running to the outside or cutting back inside. The defenders has to do an up-down before flowing with the ball carriers and reacting to make the tackle. Most runners used speed to get to the outside. Some got frisky and cut back inside the first dummy. Develin, on one rep, ran directly into the dummy on the far right.

--During kickoff coverage work the first unit of cover men included, from left to right, Eric Rowe, Burkhead, Jonathan Freeny, Shea McClellin, Nate Ebner, Stephen Gostkowski, Jordan Richards, Jonathan Jones, Geneo Grissom, Brandon King and Justin Coleman. The next group consisted of Thomas, Damarius Travis, Harvey Langi, Jason Thompson, Van Noy, Gostkowski, Bates, Kenny Moore II, Derek Rivers, Roberts and D.J. Killings.

--Both Langi and Deatrich Wise Jr. continued to get high-level reps on defense at outside linebacker and left defensive end, respectively.

--It's worth nothing that Ebner and Richards have had a lot of reps in camp as the deep, single-high safety in various groupings. That's in part due to Harmon's absence, but is notable because it would seem to be a bit counter to the players' builds and perceived styles of play.

--Late in practice the field goal unit ran on to attempt a kick in the 45-yard range after an offensive play. Gostkowski missed his first attempt wide left but appeared to find success on ensuing kicks although it's always hard to tell from the media tent.

--Belichick wore flip-flops and a cut-off sweatshirt to his morning press conference. When he appeared on the practice field mere minutes later he'd put on a t-shirt under the sweatshirt while donning socks and sneakers.

--The top line working during the opportunity reps consisted of LaAdrian Waddle, Ted Karras, Cole Croston, Jamil Douglas and Cameron Fleming. Waddle actually filled in for Solder in some team reps early in practice, while Karras continues to work at both guard and center.

--Brady signed autographs for fans surrounding the field after practice. Interestingly, as he so often does, Brady turned his practice jersey inside out after finishing the workout and before interacting with fans.

--The offensive linemen, as a group, also signed autographs.

--A number of defensive players did some extra conditioning work after practice ended, a group that included King, McClellin, Van Noy and Brooks Ellis.

--Grissom worked by himself with a large blocking dummy after practice.

--T Conor McDermott also stayed out late working by himself at the far end of the field.

--Those players talking to the media after practice included Butler, Gilmore, McCourty, Lucien and Lawrence Guy. For what it's worth, Gilmore had his right hand wrapped, something that was obvious while holding his helmet as he spoke to reporters.