After facing Duke in Chapel Hill tonight, North Carolina's basketball team will have to play eight games -- all against ACC opponents -- over the course of the next 31 days.

Four of those eight will be on the road, including trips to Virginia, N.C. State and Boston College. Plus, there's the return match against Duke in Durham on March 8 in the final game of the regular season.

That's why Tar Heels coach Roy Williams won't play Ty Lawson unless it's a medical certainty that the standout point guard's sprained left ankle is immune to additional damage.

Lawson, wearing an air cast, did some light shooting at Tuesday's practice. But Williams said he was on crutches earlier in the day. The good news is that his injury is considered an ankle sprain, which generally heals more quickly than a "high" ankle sprain.

While any Duke-Carolina basketball game is a matter of be-all, end-all urgency for the teams' fans, that's not really the case for the teams.

Obviously, Williams and Duke coach Mike Krzyzewski want to win this one and will go to great lengths to do so. But the more pressing objective is to get to Raleigh's RBC Center for the first weekend of NCAA Tournament games (March 21 and 23), and if possible, to Charlotte for the East Regional semifinals (March 27 and 29).

The first part of that goal should be a lock for both teams. It's difficult to imagine either team being sent out of the Triangle for the opening weekend by the NCAA selection and placement committee. But for Carolina, that presumption hinges on getting Lawson back to full speed for as many games as possible. Even with Lawson in the lineup, the Tar Heels struggled to win at Clemson and Georgia Tech and lost to Maryland in Chapel Hill.

At 21-1 overall and 6-1 in the conference, Carolina has won with its usual consistency. But that imposing record makes it easy to lose track of the fact that the Heels have an unbalanced offensive equation. For long stretches of most games, starters Marcus Ginyard and Deon Thompson don't score enough to become major defensive concerns for opponents.

With point sub Quentin Thomas in the mix, the team's offensive options are reduced even further. His job is to take care of the ball, not to look for shots.

Most basketball coaches are masters of percentage thinking. If they see the slightest chance to use 5-on-4 or 5-on-3 defensive strategies, they'll go that route until an opponent forces them to try something else.

Without Lawson, the Heels have three reliable scoring threats -- Tyler Hansbrough, Wayne Ellington and Danny Green, none of whom is exceptional at creating individual offense. But even if those three could combine for 50-60 points per game, the margin for error would be still be narrow in most conference games.

Make someone other than Hansbrough, Ellington and Green score enough points to beat you. That will be the prevailing defensive theory against Carolina for as long as Lawson is sidelined.

It's big-picture time for Williams and the Tar Heels. The hated Blue Devils may be on the doorstep. The emotional undercurrent will be feverish. There'll be a hundred replays of Gerald Henderson's foul against Hansbrough in last season's game at the Smith Center. Lawson will want to cowboy-up.

But there are miles yet to ride for Carolina, and Williams won't risk a season over one game unless he's sure there's no risk involved.