Takeo Spikes hurt his right Achilles in the Buffalo Bills' 24-16 loss to the Atlanta Falcons on Sunday, an injury that could end the Pro Bowl linebacker's season if the tendon is torn.
Coach Mike Mularkey wouldn't speculate on the extent of the injury, saying he'll know more Monday.
"He's the pulse," safety Troy Vincent said of the eight-year veteran and two-time Pro Bowl selection. "I don't know how bad it is, but it could be devastating."
Spikes was hurt in the second quarter while pressuring Atlanta quarterback Michael Vick deep in the Falcons' end.
He lay on the field face-down for a few minutes, then rolled over and slammed his helmet to the ground. After being helped to the sideline, Spikes appeared in tears as he was taken away on a cart. Angelo Crowell replaced him for the remainder of the game.
The Bills defense was already banged up: linebacker London Fletcher is nursing a hamstring injury, and safety Lawyer Milloy is playing with a protective cast on his right thumb.
Falcons CB DeAngelo Hall hurt his shoulder when he tackled Willis McGahee for no gain on the final play of the first quarter.
New England Patriots safety Rodney Harrison, the NFL's career leader for sacks by a defensive back, injured his left leg in the win over Pittsburgh and was taken off the field on a stretcher. With the Steelers driving midway through the first quarter, Pittsburgh wide receiver Cedrick Wilson was taken down from behind, causing him to roll into Harrison's path and take out the safety's left leg.
The injury was the second of the day for a New England defense that went in without two of its top three cornerbacks, Tyrone Poole (ankle) and Randall Gay (ankle). Cornerback Duane Starks injured a wrist on the Steelers' first play from scrimmage.
In Seattle, Arizona Cardinals quarterback Kurt Warner injured his right groin while scrambling during the second quarter. Seahawks starting cornerback Andre Dyson also left the game after becoming sick in the first quarter.
Facing a third-and-9 at the Seattle 32 with 3:56 left in the first half, Warner was pressured and ran to his left. After throwing across his body, Warner began limping back toward the center of the field before going down and grabbing his right leg. He was replaced by Josh McCown on Arizona's next possession.
Arizona also lost nose tackle Russell Davis (biceps), linebacker Eric Johnson (left hamstring), and cornerbacks David Macklin (left hamstring) and Antrel Rolle (left knee) to injuries in the second half.
The New York Jets lost both starting quarterback Chad Pennington and his backup, Jay Fiedler, to shoulder injuries in an overtime loss to Jacksonville. Although Pennington returned when Fiedler went down, he was clearly hurting; each is scheduled to undergo an MRI on Monday.
Pennington, who had offseason surgery to repair a torn rotator cuff in the same shoulder, was sacked on consecutive plays during the Jets' first series of the second half. Neither Pennington nor coach Herman Edwards wanted to speculate on the severity of the latest injury, but the quarterback said his shoulder felt "similar to last year."
Fiedler came in and led the Jets' next drive. But he was hit while completing a 16-yard pass — his sixth play in place of Pennington. Fiedler jogged off the field and into the locker room.
"I knew I wasn't going to be able to throw a football," Fiedler said.
Jets offensive tackle Jason Fabini left the game in the fourth quarter with an injured right knee and will have an MRI; linebacker Eric Barton has a sprained ankle. For the Jaguars, offensive tackle Maurice Williams sprained his right knee in overtime and right guard Chris Naeole also sprained his left knee, but coach Jack Del Rio said neither was serious.
Philadelphia Eagles' kicker David Akers, who hurt his right hamstring in last week's win against San Francisco, appeared to reinjure the muscle during the opening kickoff against visiting Oakland. He later returned to make the game-winning field goal.
Akers came up limping after his first kickoff attempt, but a penalty was called and Philadelphia was forced to kick again. After the second attempt, he fell down and was helped off the field.
But another penalty was called, and third-string tight end Mike Bartrum was forced to kick off. The Eagles later used linebacker Mark Simoneau to try an extra point; his first attempt was blocked.
Akers returned to the game, however, to make a 23-yard field goal with 9 seconds left to lift the Eagles to a 23-20 victory.
"You know it's going to hurt for one second and then the game is over," said Akers, a two-time Pro Bowl kicker. "My whole leg hurts right now."
In St. Louis, Rams running back Steven Jackson missed the start of the second half with a rib injury; X-rays indicated no breaks. Jackson was back on the sideline and in uniform midway through the third quarter, but he didn't return.
The Rams were also without wide receiver Isaac Bruce, who sustained a turf toe injury near the end of the half.
Vikings defensive end Lance Johnstone left Minnesota's game against visiting New Orleans with a sprained shoulder, and cornerback Brian Williams did not return after spraining his knee in the second quarter. Minnesota was already playing without three injured starters: wide receiver Nate Burleson (sprained left knee), linebacker E.J. Henderson (sprained right ankle) and free safety Darren Sharper (sprained left knee).
The Bears lost tight end Desmond Clark to a neck strain in the first half of a home loss to Cincinnati.
In Miami, linebacker Junior Seau hurt his calf in the second half, and safety Tebucky Jones hurt his hamstring in the second quarter.