Mike Krzyzewski was worried going into Saturday's game with Boston College. He was worried about a "Carolina hangover." And he was well aware that despite its now-glittering 21-1 overall record and 9-0 ACC record, this Duke team walks a fine line. The margin for error is slim.

The coach who now has 796 career wins knows that this team, with just one senior who plays regularly, is not the powerhouse of those Laettner, Hurley and Hill teams that won back- to-back national titles. Nor does it have the talent of the Shane Battier-Jason Williams-Carlos Boozer team that took the 2001 championship. And it certainly doesn't have the strength and talent of that 1999 Elton Brand-led team that finished 37-2.

Mike Krzyzewski knows this and says it often. He said it Saturday.

Coach K believes that this Duke team has to lay it out on the floor every time out. If not, they're in trouble. And sure enough, Duke was in trouble in the first half Saturday, trailing Boston College at Cameron, 42-41, at intermission. He knew the emotion of the big Carolina win could have an effect against B.C.

"I was more worried about this game than North Carolina," Krzyzewski said after Duke's hard-fought 90-80 win over Boston College. "Not that I was sure we were going to win Wednesday, but I was sure that we'd be ready, sure that we were going to be there. This one, the last two days I've been on them like crazy. We just weren't sharp.”

No, Duke wasn't as sharp as they had been. But they were good enough. A team that wants it badly enough can overcome a lot of obstacles. And if anything, this Duke team battles.

One thing that Coach K has gotten his teams to do consistently over the years is to play hard. And this team plays hard.

Unlike last season’s troubled group, this one is having a good time doing it. You see the joy they have playing basketball. It's on their faces. It's in their body language.

No, Duke won't overpower other teams. but they scratch and claw. Boston College, led by Tyreese Rice's 28 points, shot 55 percent. Duke forced 21 turnovers, however, which translated into 21 Blue Devil points. And while they weren't bombing 3s with great accuracy, they hit some clutch ones, especially the back-to-back, back-breakers by the freshman Kyle Singler (24 points,10 rebounds) that gave Duke a 13-point, second-half lead.

"Kyle's a beast," sophomore Lance Thomas said afterward. "Obviously, he can shoot the ball. Kyle's just a complete player."

As is the captain, senior DeMarcus Nelson, who sliced his way to 23 points. Nelson said Duke's lethargy was taken care of at halftime.

"I don't think that we had the mind-set of competing at the highest level as a team,” said Nelson, who also had eight rebounds and five assists. "In the second half, Coach K said some things to us, I said some things and we got our edge back. We got our fight back."

And that's been the key in this 21-1 start. Duke will fight. They're not the biggest or the quickest or the most talented, but so far they're playing with heart, with a determined will and with a style that suits the players they have.

There are teams with more overall talent. I still believe, rightly or wrongly, that a healthy Carolina has the best talent in the league and has a more legitimate shot than Duke to win the national title.

Right now, though, it is Duke that is playing like a champion. They're running and gunning and getting after it defensively. They make others play their game.

So as February moves quickly along and the madness that is March looms on the winter horizon, teams better be prepared to lay it out when they face the Blue Devils. Duke surely will.

Even if they're not at their best.