BETHLEHEM, Pa. - DeSean Jackson and Stewart Bradley, two of the Eagles' most important players, sat out practice Sunday, and more Birds might join them on the training-camp sideline Monday.

That's because running back Mike Bell, cornerback Asante Samuel, guard Max Jean-Gilles, and center A.Q. Shipley each left practice early with a range of injuries.

It was only the third day of full-team practices at Lehigh University. Six weeks remain before the Sept. 12 season opener.

Bell's injury, at first glance, appeared to be the most serious: The hard-running No. 2 halfback pulled up while running in the open field and crumpled to the ground, grasping his left hamstring.

After a strong morning practice, Bell cursed when trainers had to cart him off the field.

Wide receiver Jackson was out with a back strain suffered in Saturday's practice, according to the team. Bradley sat with a hamstring spasm in his right leg, the same side on which he suffered a torn anterior cruciate ligament last year.

Bradley's injury sounds mild, but it represents another speed bump in his attempt to return to the field and highlighted the Eagles' potentially precarious situation at middle linebacker.

The critical position lies in the hands of Bradley and Omar Gaither, two players who are trying to return from significant physical problems in 2009.

With those two hurt, the team cycled through six different starters in the middle last season, but the only insurance brought in for 2010 was Jamar Chaney, a seventh-round draft choice out of Mississippi State.

Instead of adding reinforcements, the Eagles are counting on Bradley to return as a physical force and leader. So far, though, he has been bothered by nagging injuries. He also missed June practices with a left calf injury.

Defensive coordinator Sean McDermott downplayed concern about Bradley, whom he has called the quarterback of his defense.

Head athletic trainer Rick Burkholder "feels good about it, Stew feels good about it, and so does [coach Andy Reid]," McDermott said. "We look to have him back very soon."

Gaither filled in for Bradley on Sunday. The five-year veteran, who is coming back from a Lisfranc foot sprain that ended his 2009 season after five weeks, said he and Bradley will be fine.

Gaither noted that he has started at middle linebacker before, holding the top spot in all of 2007 and most of 2008.

"I've done it for an entire season, so when I go in, it's just like it's real seamless," Gaither said.

The team listed Bradley as day-to-day and had the same prognosis for Jackson.

Bell had a strong morning practice, pounding the ball on inside runs and blasting Trent Cole off his feet on a pass-blocking assignment, and was off to a good start in the afternoon before he got hurt. He caught a pass over the middle and was accelerating away from linebacker Keenan Clayton when he pulled up and dropped to the ground.

He was audibly angry. The injury came just a few hours after he had expressed great optimism about the season.

"I expect the best out of myself and I really don't think I've reached it yet," Bell said after the morning session, before he got hurt.

Bell later left the locker room with his left leg in a compression wrap and, clearly not in the mood to talk, said simply, "I'm all right."

He did not appear to have a noticeable limp.

Samuel also seemed to be walking without a problem. He had quietly ridden off the field in a cart. While losing Samuel would be a significant blow, there seemed to be little cause for concern Sunday. Samuel's left hamstring injury went almost unnoticed at the time it happened, and he cracked jokes afterward when talking about his prognosis.

"I'm not a mad scientist," he said. "I might be out there tomorrow."

Dimitri Patterson took his place in practice.

Jean-Gilles, who had off-season lap-band surgery to lose weight, was dehydrated, the Eagles said. He gave a thumbs-up to reporters as he got into his truck.

The problem sounds minor, but if it persists, it could add to the worries on an already wobbly offensive line. The Eagles already have an ailing guard, Todd Herremans, who is out with a foot injury. Jean-Gilles was filling in for him. Mike McGlynn stepped into Jean-Gilles' guard spot in practice.

The line is also missing center Jamaal Jackson, who is recovering from knee surgery.

Shipley is competing to take Jackson's place, but he hurt his ankle in the late session. He had been limping earlier in the day.

Contact staff writer Jonathan Tamari at 215-854-5214 or
Staff writer Jeff McLane contributed to this article.