"I only know one thing, and it's to play as hard as I can," the quarterback said. "I'm not trying to pull a Willis Reed out there, but if I can play, I can play."

Kitna was knocked out of the game with a concussion, only to return and set up Jason Hanson's 37-yard field goal in overtime that lifted the Lions to a 20-17 victory over the Minnesota Vikings on Sunday.

"I don't think he knew where he was," Detroit receiver Roy Williams said. "He might've thought he was back at Central Washington, but he led this team to a victory."

Kitna said it was the worst concussion of his 11-year career, and the first since 2000. He was knocked out of the game in the second quarter and didn't appear as if he was going to come back in as he stood on the sideline without his helmet.

Kitna finished 22-of-33 for 245 yards with one touchdown and an interception.

"I've seen a lot in this league, but that was special," Lions coach Rod Marinelli said.

J.T. O'Sullivan, who hadn't thrown a pass in the NFL until Sunday, was 13-of-23 for 148 yards with a score, two interceptions and a fumble in Kitna's place.

The Vikings also lost their starting quarterback when Tarvaris Jackson threw an incomplete pass on the first snap of overtime and left the game with a groin injury.

Jackson, who tied a team record with four interceptions, was replaced by Brooks Bollinger. There was no immediate update on Jackson's status.

Minnesota wide receiver-kick returner Troy Williamson left the game with a hamstring injury, while Lions tight end Dan Campbell injured an elbow.

Elsewhere, Pittsburgh outside linebacker James Harrison was taken off the field on a stretcher with a neck injury after being hurt on the final play of the first half of the Steelers' 20-3 win against Buffalo.

Harrison was hurt on Marshawn Lynch's 8-yard carry that ended the second quarter. He became caught up in a pileup while he was being blocked and he rammed his head into teammate Casey Hampton's back as Lynch was tackled by Brett Keisel and Clark Haggans.

The Steelers announced only that Harrison would not return to the game. After being examined for a few minutes, Harrison returned to the sideline midway through the third quarter and was walking freely.

It was a scary sight after Bills tight end Kevin Everett sustained a life-threatening spinal cord injury against Denver last week. After doctors initially said he might be paralyzed, Everett showed significant improvement in only several days. By the end of the week, doctors said Everett could wiggle his toes, bend his hip, move his ankles, elevate and kick his leg, as well as extend his elbows and slightly flex his biceps.

"It made you a little nervous after what happened last week," defensive end Aaron Smith said.

Houston wide receiver Andre Johnson, who caught seven passes for 120 yards and two scores in the Texans' 34-21 win at Carolina, left with a sprained left knee.

Johnson said he would undergo an MRI on Monday, but was hoping he would play next week against Super Bowl champion Indianapolis in an early season showdown in the AFC South.

New York rookie receiver Steve Smith was knocked out of the Giants' 35-13 loss to Green Bay with a shoulder injury.

Smith caught a 10-yard pass late in the first quarter and later left the field for X-rays, which disclosed an injury to his shoulder blade.

Backup quarterback Jared Lorenzen sprained an ankle on the Giants' final drive and was forced to leave the game around the two-minute warning. He was taken for X-rays, but the team had no immediate word on the extent of his injury. Anthony Wright, the Giants No. 3 quarterback, replaced him.

Arizona wide receiver Larry Fitzgerald, who caught seven passes for 87 yards, left Cardinals' 23-20 win over Seattle after a hit from behind by Deon Grant in the third quarter, but returned a short time later.

Chicago punter Brad Maynard missed a game for the first time in his career, ending a streak of 161 consecutive games when he sat out the Bears' 20-10 win over Kansas City because of a groin injury. The Bears signed Dirk Johnson to replace Maynard, and he got hurt late in the third quarter.