PITTSBURGH — Tyrone Carter isn't the player that Troy Polamalu is. Doesn't pretend to be. There's only one Troy Polamalu, Carter agrees, and not even a former college football defensive back of the year can replace him.

With Polamalu out for three to six weeks with a torn medial collateral ligament, the Pittsburgh Steelers will turn to the player who always seems to be there when needed. When safety Ryan Clark's spleen was damaged by playing in the thin air of Denver two years ago and was lost for the season, Carter helped replace him, too.

Not surprisingly, the Steelers are convinced that if there is one player who has the confidence and the toughness needed to fill in for one of the NFL's best defensive players, it's Tyrone Carter.

This assignment isn't easy, but Carter's life hasn't always been easy, either. Not with a son to raise while he was in high school, an idolized brother who's in prison and a wife who has been in a wheelchair for nearly four years.

"I have all the faith in the world in him," Clark said.

Carter believes in himself, too, and it's not like he hasn't been through this before.

"You're really only one play away from starting," Carter said. "It's not like in college, where you have redshirt freshmen and you're three-deep. You're two deep (in the NFL), and you have to prepare like that. That's what makes a professional. If you're not like that, you'll be out of the league in no time."

This is Carter's 10th NFL season, which is a testimony to his perseverance, adaptability and patience.

Carter also wasn't the star, was the backup in a different sort of way, while growing up in Pompano Beach, Fla. His older brother, Tank, was the star of the family, a big hitter who enjoyed the contact and physicality of football.

The brothers were raised by grandparents who also brought up 13 other children. Carter was raising his own child, a son born while he was a high school junior, even before his grandmother pushed him to attend the University of Minnesota, partly so he would avoid the temptations of street life. Tank didn't make it to college, having dropped out of high school.

Carter excelled at Minnesota, winning the Jim Thorpe Award as college football's best defensive back in 1999, but his size — he is 5-foot-9 and 195 pounds — pushed him down to the fourth round of the NFL draft.

He stayed in Minnesota to play for the Vikings for three seasons, then went to the Jets for one. He hooked on with Pittsburgh midway through the 2004 season and has been there since, making four interceptions and 106 tackles while playing 73 games, starting 10. The Steelers' game Sunday in Chicago will be start No. 11.

Even when the Steelers made it to the Super Bowl in February 2006, Carter learned again the pressures of playing football can't begin to compare to the pressures and downturns of life.

Not long before that Super Bowl, his wife, April, was paralyzed from the waist down during an all-terrain vehicle accident. The couple has a daughter, Tyra, who was born after the accident, one of Tyrone Carter's four children.

About the same time, Tank Carter was sentenced in Florida to six months in jail for driving with a suspended license.

However, he declined to report to jail in January and chose instead to accompany his younger brother during the Steelers' playoff road run in which they won in Cincinnati, Indianapolis and Denver before beating Seattle in the Super Bowl in Detroit.

"That's the brotherly bond we have," Carter said.

When he finally reported, Tank Carter was given an additional 4Z\x years prison time by a judge, and isn't scheduled for release in October 2010. Still, Tank Carter told his brother it was worth it because he got to see his little brother win the Super Bowl.

By being in prison, however, Tank Carter didn't get to see Tyrone win another one — and in Tampa, near their hometown — in February.

Yes, the Steelers know Tyrone Carter doesn't have Polamalu's speed or big-play ability, but they're not worried about him handling the pressures of the job.

"Any time he's ever stepped in, he's done as good a job or a better job," Polamalu said. "You couldn't imagine there would be any drop-off."