PHILADELPHIA -- Quarterback Kevin Kolb's head slammed into the turf, his eyes closed for several seconds and he was slow to get up and walk to the sideline.

Linebacker Stewart Bradley flew headfirst into a teammate's leg. He was on all fours, struggled to get up on his own power, stumbled for a few steps and toppled to the ground.

Both Philadelphia Eagles briefly returned to play after the punishing collisions.

Both had concussions.

They weren't the only aching Eagles.

Pro Bowl fullback Leonard Weaver and center Jamaal Jackson could both be out for the season after they were seriously injured in the Eagles' 27-20 loss to the Packers on Sunday. Weaver has a torn ACL in his right knee and Jackson has a torn triceps on his right arm, part of a lengthy injury list that darkened an already abysmal opener.

Coach Andy Reid defended his decision to let Kolb and Stewart return because "they were fine" after early testing.

"All the questions that they answered with the doctors registered well," Reid said. "But as it went on, they weren't feeling well, so we took them out."

Kolb's game was cut painfully short after his three-year wait to succeed Donovan McNabb. Kolb's injury allowed Michael Vick his first chance to play meaningful minutes in four years when he was with Atlanta.

There's no guarantee Vick will get more -- Reid said Kolb will start if cleared to play at Detroit.

Kolb was hurt in the second quarter when he was driven into the ground from behind by Packers linebacker Clay Matthews. Kolb, who fumbled the ball out of bounds, looked pained as he rolled over and rested his face on the ground.

Kevin Kolb threw only 10 passes on Sunday (completing five) before leaving with a concussion. AP Photo/Matt Slocum

Kolb, making his third career start, was looked at by trainers for several minutes on the Eagles sideline. He returned to the game for one more series and threw three short incomplete passes.

Kolb was 5 for 10 for 24 yards and was sacked twice.

The Eagles first said Kolb had a jaw injury, but it proved far more serious. Vick replaced him to start the second half and led the Eagles on a touchdown drive. Vick threw a TD pass and was 16 of 24 for 175 yards.

Kolb was making his ballyhooed debut after McNabb's April trade to NFC East rival Washington. Kolb started two games last year after McNabb got hurt in the opener. He put up impressive numbers, becoming the first player in league history to throw for 300 yards in his first two starts.

Kolb was horrible in the first half, throwing an interception that was overturned by replay.

Vick played at times like the No. 1 QB he so desperately wants to be. He showed off his former dazzling form on a 31-yard run that led to LeSean McCoy's 12-yard TD run.

Reid tried to sway talk away from a potential quarterback controversy.

"I'm not looking to the future, I'm trying to get the offense fixed so that we can win some football games here," Reid said.

Vick was a rare bright spot on an injury-filled day.

Bradley was hurt when his head slammed into teammate Ernie Sims while they both tried to tackle Greg Jennings. Stewart struggled with his balance and collapsed. Like Kolb, he returned to play with a head injury before leaving for good.