Tyler Hansbrough was unmasked against Michigan State, much to his relief. The sophomore scored 33 points, most by a Tar Heel in NCAA play since 1981, and grabbed nine rebounds. More importantly, his North Carolina team was revealed as well, emerging as the championship contender indicated by its top seed in the East Region.

The 81-67 victory over the ninth seed sent the Tar Heels to the Sweet 16 for the 27th time in program history, and proved something about a squad whose intensity and resolve had been questioned. “From a toughness viewpoint, this was pretty impressive,” coach Roy Williams said.

Williams and Michigan State’s Tom Izzo, two of the premier coaches in the college game, stood chatting amiably in front of the Spartan bench for an extended period prior to tipoff, two friends awaiting their East Regional encounter. Then play began and their teams stood toe to toe and exchanged blow for blow, one of the nation’s top offenses going at one of the college game’s stingiest defenses.

For 34 minutes neither team gained control. The lead changed hands 12 times in barely nine minutes as the second half wound down, and the game appeared headed for a frantic finish.

But, after Hansbrough made a pair of free throws to build a 64-61 lead with 5:29 remaining, the balance shifted. “It all boiled down to who was going to get the defensive stops,” said UNC senior Reyshawn Terry, who had 14 points, including a third straight late-game spurt, despite a migraine headache. “We were tough enough to get the job done.”

Drew Neitzel, an all-Big 10 guard, was carrying the load for Michigan State, almost to an extreme. The 6-foot junior had 27 of the Spartans’ 59 field goal attempts, shifting relentlessly behind teammates’ screens as Ty Lawson, Marcus Ginyard, Wes Miller and Quentin Thomas took turns giving chase.

Maneuvering for yet another look, Neitzel had the ball stolen on the wing by Ginyard, playing with a sprained ankle. At the other end the ball went inside to Brandan Wright, struggling through foul trouble. Rather than force a shot, the freshman passed out to classmate Lawson, “a tough little nut,” according to Williams. The playmaker’s 3-pointer at the 4:51 mark, the highlight of a 20-point, 8-assist performance, increased the lead to two baskets. Michigan State never got within five points again as the Tar Heels closed with a 23-8 rush.

“For 36 minutes we gave them a hell of a game,” Izzo said.

Not good enough. In a 40-minute game, the Tar Heels wore down yet another opponent and ultimately imposed their will as they improved to 30-6.

Their 13-rebound edge was the most achieved this year against Michigan State. “It was a huge focus for us,” Williams said of the board work. Against one of the nation’s leaders in field goal percentage defense (.381), the Heels made 48.1 percent of their shots. They scored 81 points on a team that limited opponents to an average of 56.5, third-best in Division I. And while this was a Michigan State team that stumbled down the stretch, its profile much like that of Duke, with seven losses in 12 games prior to the NCAAs, the Spartans were no easy out.

The competition will stiffen the farther the Tar Heels advance. But, like Hansbrough, they seem to be reaching a new comfort level.

The team’s top scorer and rebounder played four full games wearing first one, then another clear plastic mask to protect his nose, fractured against Duke in the regular season finale. The Michigan State game promised to be a fifth, but after about seven and a half minutes of play he shed his artificial skin. “I was frustrated,” Hansbrough said. The mask heated up his face, and was as irritating as a bee persistently buzzing about his head. “I felt more comfortable with it off.”

Apparently so. Hansbrough’s 33 points were the most scored by a Tar Heel in the NCAA tournament since Al Wood had 39 in the 1981 Final Four. (His career high is 40 points, scored last season against Georgia Tech.) His 38 minutes were the most of his career. Best of all, his relentless interior play, his combination of skill, talent and determination set the tone for a young team coming into its own at just the right time.