Williams was injured when he was being cut block by J.R. Sweezy and his left ankle was caught underneath as Sweezy made the block on a 2-yard run by Marshawn Lynch.
Only Matthews returned in the first half.
The Colts suffered their second significant injury of the week when left guard Donald Thomas tore a quad tendon in his right leg in Indianapolis' loss to Miami. He will likely miss the rest of the season. Colts coach Chuck Pagano said Thomas will need to have surgery.
Floyd immediately went down on the incomplete pass and players from both teams took a knee around him,Cheap NFL Jerseys China. Team doctors from both sides tended to Floyd before he was put on a stretcher and wheeled off the field,Alex Iwobi Arsenal Jersey UK.
It's yet another big blow for a team that also lost starting running back Vick Ballard this week with a torn anterior cruciate ligament in his right knee.
The Falcons also lost linebacker Sean Weatherspoon (foot), defensive end Kroy Biermann (right ankle), fullback Bradie Ewing (shoulder), defensive end Cliff Matthews (neck) and cornerback Asante Samuel (thigh) in the first half.

Later, Meriweather left the game as well with a concussion following another hard-hitting play.
Running back Eddie Lacy left the Packers' home opener with a concussion after what appeared to be a helmet-to-helmet hit by Redskins safety Brandon Meriweather.
Rams safety Matt Daniels was carted off the field with his right ankle in a splint in the first quarter and did not return.
Branch got hurt rushing Jacksonville quarterback Chad Henne in the first quarter and had to be helped off the field. Coach Dennis Allen said after the game the injury looks to be "significant,Wholesale Nike NFL Jerseys."
As for Thomas, Rivera would only say the player will be evaluated through the week under the NFL's concussion protocol. Rivera had no update on Mikell.
Oakland strong safety Tyvon Branch and Jacksonville running back Maurice Jones-Drew left the Raiders' 19-9 victory over the Jaguars with ankle injuries.
Jones-Drew also got hurt in the first half and did not return. Coach Gus Bradley said Jones-Drew sustained a sprain and X-rays were negative. He will be evaluated Monday.
Ewing, who couldn't put weight on his right leg, left the field on a cart. Weatherspoon, Ewing, Biermann, Samuel and Jackson — all starters — did not return to the sideline for the second half.
Reid was injured when he came up to hit Sidney Rice on a completion across the middle.
Ravens running back Ray Rice left Baltimore's game against Cleveland with a strained hip flexor,Wholesale Authentic Jerseys. He went down without contact with 12:01 left in the game.
"He's doing fine," coach Mike McCoy said. "All the tests right now look good. It's great for the organization to go out and get a win for Malcom. I'll leave it at that and update you as time goes on."
Starting safety Charles Godfrey hurt his right Achilles tendon,China Jerseys Wholesale, and starting cornerback Josh Thomas sustained a concussion in a 24-23 loss to the Buffalo Bills. Starting safety Quintin Mikell also didn't return after hurting his right ankle in the second half.
San Francisco lost starting nose tackle Ian Williams to a leg injury in the first quarter against Seattle and safety Eric Reid to a concussion in the second quarter.
Falcons running back Steven Jackson left the game against the Rams — his former team — with a first-quarter thigh injury, the first of a long list of injuries for Atlanta.
Carolina's already young and inexperienced defensive secondary is suddenly being hit by injuries.
Floyd was down for several minutes in the third quarter of San Diego's 33-30 win after he was wrapped up from behind by safety Nate Allen and had his head driven into charging linebacker DeMeco Ryans.
PHILADELPHIA (AP) — San Diego Chargers wide receiver Malcom Floyd left Sunday's game against the Philadelphia Eagles with a neck injury after he was sandwiched on a hard hit.
Also,Andrea Barzagli Jersey, Seattle starting left tackle Russell Okung was injured on the final play of the first quarter, suffering a left foot injury. He limped off the field and was later taken to the locker room on a cart to be examined. He returned to the sideline but was a spectator.
Floyd had five catches for 102 yards before the injury.
Panthers coach Ron Rivera called Godrey's injury the most s