It was a rough week for NFL linebackers in Week 1, most notably Baltimore's Terrell Suggs.
Baltimore's six-time Pro Bowl selection tore his left Achilles in the Ravens' 19-13 loss to the Denver Broncos on Sunday, coach John Harbaugh announced after the game.
"I don't even know what happened out there," Harbaugh said. "All of a sudden, I look back and he was on the ground. But these are the things in life that happen. Adversity is all about how you respond to it, how you react to it."
Ravens linebacker Elvis Dumervil said it was a huge loss.
"You can never replace a Terrell Suggs, a big emotional leader for our team," Dumervil said. "It hurts everybody, whenever you hear news like that."
Two-time Pro Bowl selection Luke Kuechly, who just became the league's highest-paid middle linebacker on Thursday, left Carolina's game against Jacksonville in the first half after sustaining a concussion on a fairly basic tackle against Jaguars running back T.J. Yeldon.
Kuechly, who has never missed a game in his first three seasons, wobbled as he got up and then dropped back to the ground again. He appeared a little woozy as he left the field.
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Kuechly will enter the concussion protocol and be re-evaluated later in the week.
Jets rookie linebacker Lorenzo Mauldin had a scary moment after he was injured, carted off and taken to the hospital. The Jets later announced Mauldin has a concussion -- but no neck injury, as initially feared -- and was awake and had feeling in all of his extremities.
The third-round pick out of Louisville appeared to punch the ball out of quarterback Johnny Manziel's hands and Darrelle Revis recovered deep in Browns territory.
Mauldin remained on the ground for several moments right after the play, face-down on the turf.
Green Bay Packers linebacker Sam Barrington left his opener against the Chicago Bears because of an ankle injury.
In other injury news:
• Two starting quarterbacks left with injuries -- Cleveland's Josh McCown and Oakland's Derek Carr. McCown suffered a concussion and was replaced by Johnny Manziel, who threw his first touchdown pass.
Carr left with a hand injury and was replaced by Matt McGloin.
• Indianapolis Colts wide receiver T.Y. Hilton left Sunday's loss to Buffalo with a knee injury. He had seven catches for 88 yards.
• Cardinals running back Andre Ellington was carted off in the fourth quarter with a right knee injury against the New Orleans Saints. Ellington had accounted for more than 1,000 yards from scrimmage in his first two seasons.
• Washington Redskins wide receiver DeSean Jackson hurt his left hamstring in the first quarter against Miami and did not return. The Redskins also lost safety Duke Ihenacho to a left wrist injury.
• Bills safety Corey Graham, Rams cornerback Trumaine Johnson and Dolphins tight end Dion Sims left with head injuries.
• Jacksonville left tackle Luke Joeckel left with a left ankle injury.
• Jets cornerback Antonio Cromartie departed in the second quarter with an injured left knee.