One positive spot in Duke’s poor basketball season? The ‘sensational’ Mark Williams.

A month ago, Mike Krzyzewski saw into the future.

His Duke Blue Devils lost 91-87 to rival North Carolina at Cameron Indoor Stadium on Feb. 6.

Krzyzewski had 7-0 freshman center Mark Williams in Duke’s starting lineup but only played him for 15 minutes against UNC’s cadre of big men.

“It was so physical inside, and he was not ready for that level,” Krzyzewski said of his young center. “He will be.”

Since then, slowly but surely, Williams has done just what his coach predicted.

Over Duke’s last three games, Williams has played 28.6 minutes per game, averaging 15.1 points, eight rebounds and 2.9 blocked shots.

On Tuesday night, when Duke lost 81-77 in overtime at Georgia Tech, Williams saw his most extensive playing time of the season facing Moses Wright, the Yellow Jackets’ veteran 6-9 center.

Williams scored 20 points, hitting all nine of his shots, with seven rebounds, three blocked shots and three steals.

Krzyzewski called his performance -- in 35 minutes of play before he fouled out -- “sensational.”

And that brings us back to Duke preparing to face UNC a second time.

On Saturday night at the Smith Center, the Blue Devils and Tar Heels will face off in the regular-season finale.

This time, his recent play shows, Williams appears far more mentally and physically prepared to play against UNC’s frontcourt featuring 6-11, 265-pound freshman Day’Ron Sharpe, 6-10, 240-pound sophomore Armando Bacot, 6-10, 240-pound senior Garrison Brooks and 7-1, 245-pound freshman Walker Kessler.

“He’s obviously more ready, by far, than he was,” Krzyzewski said, “and that was just a few weeks ago.”

Williams in the starting lineup

He got there by working hard with assistant coach Nate James away from games and learning on the fly during them. It hasn’t always been easy.

Though Williams started the Feb. 6 game with UNC and remained in the starting lineup for every game since then, his production has wavered.

Playing against ACC blocked shots leader N.C. State’s Manny Bates on Feb. 13, Williams scored 13 points with five blocked shots, but also five turnovers, as Duke beat the Wolfpack 69-53.

A week later, Williams didn’t have a point or a rebound while playing only seven minutes in Duke’s 66-65 win over Virginia. Jay Huff, the Cavaliers’ 7-1 redshirt senior center, had skills Krzyzewski didn’t think Williams was ready to handle.

In the three games since then, though, Williams has become the inside force Duke needs to give them offense when jump shots aren’t falling.

“Every game it seems like Mark continues to get better,” Duke sophomore forward Wendell Moore said. “That’s what we need, especially from him. He’s a big piece for what we do. When he gets going we have a really good chance of beating anyone in the country.”

Not committing freshman fouls

Of course, Williams’ play isn’t perfect. He did foul out of the Georgia Tech game in overtime.

He has to make sure that’s not an issue against all those UNC big men. And that’s a real concern.

“Now he’s got to stay in the game by not committing freshmen fouls,” Krzyzewski said. “In trying to battle, you’ve got to use your body, not your hands and your forearms, you know, the way to legally defend in the post.”

It takes some big men a season or two to hone those skills. Williams is getting there, perhaps faster than anyone thought he could.

As a whole, the season has not gone well for Duke, especially compared to the program’s storied history. The Blue Devils (11-10, 9-8 ACC) are in grave danger of missing the NCAA tournament for the first time since 1995.

Beating UNC would be a step toward fixing that but it wouldn’t be nearly enough. Duke also would have to win multiple games at the ACC tournament in Greensboro next week, perhaps only getting in the NCAA tournament by winning the championship and accompanying automatic bid.

But amid all the ups and downs this season, having young players like Williams develop provides some solace.

“I think one of the real big pluses of the season is his development,” Krzyzewski said. “He’s going to be a real special player.”

Duke at North Carolina

When: 6 p.m., Saturday

Where: Smith Center, Chapel Hill

Watch: ESPN