IRVING, Texas (AP) -- Before Dallas picked him up last year, Ernie Sims was out of an NFL job during the season for the first time in his career.
A little more than a year later, he's supposed to be the answer at middle linebacker while the Cowboys wait for Sean Lee, their defensive leader, to come back from a hamstring injury.
Sims doesn't have much experience in the middle, and the Cowboys (5-5) take the league's worst defense into an important NFC East game at the New York Giants (4-6) on Sunday.
It's probably the closest thing to the spotlight for the former top 10 pick by Detroit since Sims started the first 50 games of his career for the Lions.
''It's a real big moment,'' the eighth-year pro said. ''A lot of eyes are on me to see how I'm going to approach the situation. I know one thing: I'm not afraid. I'm studying, meeting with Sean, meeting with anybody who is willing to give me the extra advice, the extra coaching.''
It's not like Sims hasn't started since the Lions reduced his role and later decided they didn't want him anymore, sending him to Philadelphia in an offseason trade in 2010. He made 15 starts for the Eagles that year, then another four in 13 games with Indianapolis a year later.
But he was sitting at home when the Cowboys called 13 months ago, right after Lee was lost for the season to a toe injury. He ended up making six starts for Dallas in 2012, and has three more this year.
So much for the chatter in training camp that his roster spot might be in jeopardy after he decided to rejoin Dallas as a free agent.
''The best thing I can do is not worry and not stress, don't fear anything and just go out there and do what I've been doing my whole life,'' Sims said. ''And that's playing football, doing my techniques, studying, preparing and everything else there will take care of itself.''
Fans had reason to worry after watching Sims and Bruce Carter, without Lee, in a blowout loss to New Orleans before last week's bye. With the outcome decided, the Saints ran through Lee, Carter and the rest of the Dallas defense on eight straight plays for a touchdown.
The best-case scenario was Sims and the rest just being overmatched. The worst? That they quit.
''We didn't give up at the end,'' Sims said. ''It was just a matter of getting our alignments right and executing our technique. It's been almost two weeks now. So that's the last thing on our minds right now.''
One thing is never far from Sims' mind: hitting people. Teammates usually start with ''physical'' when describing him, and that's where he begins with any self-analysis. He says his parents had to take him out of soccer when he was a kid because ''I was slide-tackling people so aggressively.''
The conversations are a little different all these years later, but the message is roughly the same.
''He's one of those guys, in a very good way, you're always saying, 'Ernie, it's shells today, you know? It's not full pads. It's not tackle,''' coach Jason Garrett said. ''You're always pulling him away from players. It's just the way he plays. Some of the best players I've ever been around have that same kind of mentality.''
So does the guy he's replacing. But Lee also has 11 interceptions in 45 games. Sims has one pick in more than twice as many games. Lee has five straight double-digit tackle games this season. Sims never had more than five in an entire season in his heyday with the Lions.
''I don't think Ernie will be Sean Lee,'' cornerback Orlando Scandrick said. ''You don't lose your captain and just find another one. Sean Lee wouldn't be Sean Lee if it was that easy. But I mean, Ernie's going to come in and I'm confident that he'll do well. He'll do fine.''
Depending on how long Lee is out, Dallas' season could be riding on it.
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